Before Team 7 meets Kakashi at the ninja academy, Kakashi had already been assessing and watching the team from a distance. When Kakashi learned that he was to be assigned Team 7, Kakashi secretly visited their residences with Hiruzen and spied on the three students from a distance to assess their behavior and personalities.

After visiting Naruto's place, Kakashi remarks, "This looks like it's going to be troublesome" and observes with disapproval that he can hardly believe that Minato and Naruto are father and son. Considering how neat and meticulous Minato was, Kakashi is shocked to find out what a slob Naruto is in comparison.

As for Sakura, Kakashi seemed to hate her parents right off the bat and find them annoying.

Upon visiting Sasuke's apartment, Hiruzen remarks that Sasuke is orderly and inherited Fugaku's disciplined nature, a sharp contrast to Naruto's messy and chaotic apartment.

Additionally, Kakashi once worked with Itachi, Sasuke's older brother, so there is already a bit of a personal connection between Sasuke and Kakashi.

Although Kakashi tells Hiruzen he still intends to keep his teamwork test as strict as ever, Kakashi seems most impressed with Sasuke's apartment, wistfully noting, "Still...this room is quite a contrast from Naruto's." Kakashi found Naruto's place disgusting and Sakura's place annoying, but his words imply that Sasuke is the first student Kakashi finds tempting to teach, noting with satisfaction the neat, disciplined state of Sasuke's room, likely reflective of the person inhabiting it. On top of that, Kakashi knew Itachi, and those two got along well...at least until Itachi turned out to be a mass-murderer, that is.

But Kakashi didn't want to be a team captain or a teacher; it's just that Hiruzen and some of Kakashi's peers were very pushy with that idea. Guy, Asuma, and Kurenai believed that teaching would do Kakashi some good, and Hiruzen was the most heavy-handed with encouraging Kakashi to teach, even though Kakashi resisted because Kakashi did not want to lead or teach his own team, expressing his doubts that he's "not cut out to be a team captain".

From a secret passage Kakashi spied on Team 7 the day their team was announced, witnessing Naruto and Sasuke's accidental kiss and the announcement of Team 7's members. Both moments Kakashi backs away from his peephole with a despondent "Heaven help me" expression on his face. He seems to perceive the boisterous trio as a nightmare to manage, not finding the trio to be appealing students.

Rather than introduce himself to Team 7 earlier and get to know them personally, Kakashi kept his distance to get a sense of the team from afar, assessing their attitudes and personalities.

Kakashi finds Sasuke tied up after Naruto attacked Sasuke in his own home, though Kakashi doesn't bother coming to Sasuke's rescue, instead leaving Sasuke alone to struggle his own way out of his predicament (even though Kakashi has been given a perfect chance to establish trust and prove himself a dependable teacher to his pupils by coming to his student's rescue...so naturally Kakashi doesn't take such an opportunity).

Kakashi isn't bothered by Naruto stealing Sasuke's identity just trick the girl he likes into kissing him, which is really messed up. Yet Kakashi doesn't try to put a stop to it.

Kakashi witnesses the infamous, "you're annoying" scene between Sasuke and Sakura. Kakashi muses, "Sasuke's words must have hurt her pretty badly", observing the quietly upset Sakura and Sasuke's influence over her. Kakashi seems surprised that Sasuke's words carry so much weight with Sakura.

When Naruto finds Sakura looking dejected and depressed, he makes the deduction that Sasuke must have said something mean to upset Sakura. Naruto is angered by Sasuke treating Sakura so poorly and rushes off to confront Sasuke in defense of Sakura.

As Kakashi watches Naruto dart off, he muses that, "Naruto doesn't understand what really happened". Interesting, since it heavily implies that Kakashi sides with Sasuke in seeing Sakura as the one at fault. It insinuates that Kakashi agrees with Sasuke that Sakura was annoying and needed to be taken down a peg or two, thus why Kakashi doesn't seem to think that Sasuke was being mean. "Naruto doesn't understand what really happened" implies that if Naruto knew what would happen, he would think Sasuke's behavior was acceptable and would react differently if he knew what really happened. Which implies that Kakashi thinks Sasuke snapping at Sakura was acceptable and that Kakashi agrees with Sasuke: Sakura was annoying and out of line.

Kakashi follows the enraged Naruto and watches Naruto challenge Sasuke for hurting Sakura's feelings, fighting on her behalf. Kakashi resumes of look of tired exasperation, as if even merely watching the rambunctious trio consumes too much of his energy (and for him, it probably does).

"Oh boy, there they go" is Kakashi's weary remark as the two boys launch into a physical fight when Naruto attacks Sasuke. Kakashi could intervene and step into help and use his adult's influence to restore order, or otherwise use this as a moment to reprimand the fighting boys and remind them that comrades should never fight each other. But Kakashi does none of these things. Instead, he hides on a roof, not bothering to resolve the conflict or use the moment for a learning moment about the importance of team camaraderie and not fighting amongst themselves.

The fight concludes when Naruto is smoothly beaten by the stronger, more skilled Sasuke. Sakura, having recovered from her despondent mood, rushes up and urges Naruto to hurry to class or else they'll be late, and the two follow Sasuke back to the academy.

After witnessing the trio's antics, Kakashi's concluding assessment of them is, "They're amusing, but they lack any sense of teamwork whatsoever. I have serious doubts that they can pass my test."

This assessment seems a bit unfair.

Kakashi is, in my opinion, being too strict, restrictive, snobby, and overbearing with his obsession with teamwork. It doesn't matter too much if Team 7 doesn't have perfect teamwork or the best team unity or cohesion. They're 12-year-olds. Kakashi's job should be to teach them teamwork, not expect them to have been programmed with stellar teamwork skills since birth. Truth is, no one is naturally adept at teamwork. Like anything else, it's a learned and taught skill, developed over time via experience and guidance. Virtuous concepts like "teamwork" aren't something humans are naturally born with; they're concepts that must be learned over time. How are Naruto, Sakura, and Sasuke supposed to learn teamwork if no one will even take the time to teach it to them? It should be Kakashi's job to teach them the value and importance of teamwork. He shouldn't expect them to have the concept perfectly down-pat right away.

Besides that, I wouldn't say from the very brief observations Kakashi made of the trio that there isn't any sense of teamwork. Kakashi is being hasty in his judgement here, not giving it much thought or looking for cues of positive traits indicative of a team capable of learning teamwork.

Naruto assaulted Sasuke in his own home, trespassed on Sasuke's property, tied up Sasuke, then slunk out and impersonated Sasuke (stealing Sasuke's identity). Yet after that list of crimes against Sasuke, Sasuke took all those slights incredibly well, because you can be sure that if my teammate assaulted me and put me in my bondage in my own home, I'd be majorly hacked and wouldn't hesitate to report them. I'd request a team transfer or otherwise refuse to work on the same team as my assaulter. But Sasuke takes such an incident shockingly well, entirely unbothered by his teammate's breach of basic respect of personal boundaries.

And so Sasuke demonstrates that he has copious amounts of patience with his teammates, a considerably larger amount of patience than the average person would have.

Sakura might have been initially rude, but even Kakashi is startled to note the extent of Sasuke's influence over her. Sakura shows that she is sensitive to her teammate's feelings and takes it hard when one of them is mad at her. Furthermore, even after her depression at being snapped at by the guy she likes, she immediately starts to behave with a more kindly towards Naruto, giving him a friendly warning that they'd better hurry or they'd be late to class. She joins her two teammates to walk back to school together, even though just a minute ago one had harshly snapped at her and the other one enjoys making her miserable and unhappy (at least that's what Sakura believes is true).

Yet Sakura is quickly forgiving to both of her two teammates, even when they're harsh or mean to her. It additionally shows she can accept and learn from criticism, always a great trait to have. Sakura doesn't brush off Sasuke's criticism or use it as reason to feel resentful towards Sasuke. Instead, she mulls over Sasuke's criticism, realizes that there might be some truth in it, and learns from it and immediately tries to better herself with that feedback by deciding to be friendly to Naruto. 

The moment Naruto noticed his teammate Sakura was deeply upset, he was immediately incensed that anyone would dare to hurt her and so boldly challenged Sasuke to a duel for being mean to Sakura, showing that Naruto won't tolerate people mistreating his teammates.

On top of that, when Naruto rebukes Sasuke for hurting Sakura's feelings, Sasuke's expression reveals that Naruto made Sasuke feel a bit guilty for snapping at Sakura earlier, showing that Sasuke isn't impervious to the feelings of his teammates either: hurting Sakura's feelings bothered Sasuke. Sasuke wasn't impervious to Naruto confronting about it, as Naruto's reprimand caused Sasuke to feel guilty over his harsh words and feel bad for hurting Sakura's feelings, which is why he suddenly seems unable to look Naruto in the eye. 

So "no sense of teamwork whatsoever"? I wouldn't say that. They are far from being incapable or inept at teamwork. I would say that from this one incident there were already several hints that Naruto, Sasuke, and Sakura are all perfectly capable of learning teamwork. With Sasuke being unbelievably patient, Sakura being impressively forgiving and able to learn from her teammates' critiques, and Naruto being fiercely protective of his comrades, I'd say that's not the worst start ever in regards to teamwork. It's a team that possess potential for learning to work together.

Yes, they have a long way to go before they learn great teamwork, since a lot of their behaviors were bad or needed a lot of buffering out, but they've just started at this point. They are basically strangers who don't even know each other. They just need someone to teach them and show them the way to teamwork - which is what a sensei is for.