Ones like Itachi, Kakashi, Jiraiya, etc. only show that just because you're a powerful shinobi, that doesn't mean you will make a great teacher.
Kakashi, like what's still happening today, was simply NOT allowing himself to truly move on from the past and his own team, so when he looked at Team Seven, all he kept doing was completely overlapping his old team over Team Seven and thus thinking that each individual was exactly like his old team was, but not being able to see (until it was too late) that each one had their own individual and unique vices that needed to be addressed.
Sakura / Rin - Rin may have had a crush on Kakashi as the "cool, stoic guy", but she clearly DIDN'T let it completely cloud her mind to everything else, much less her career as a kunoichi. She knew how to keep such things separate whereas Sakura kept letting it take over almost every time at the mere mention of Sasuke's name. Such a thing whould have been a HUGE red alert to any other competent teacher, but Kakashi seemed to figure that she would just get over it over time.
Naruto / Obito - Both may have been goofy and acted out a bit, but beyond that, Obito had a Clan, family, and real friends to turn to in times of need whereas Naruto did not plus his acting.out was for entirely different reasons; Obito was simply how he was while Naruto was doing it as a mask to hide his pain and gain acknowledgement from those around him.
Sasuke / Kakashi - Both being loners and brooders. Beyond that, they were pretty much total opposites. Kakashi became a stickler for the rules after his father's suicide, but he still also had other friends he could turn to whereas Sasuke's clan was murdered by his own brother and he didn't seem to have anyone beyond them to turn to, but again, Kakashi seemed to think this was something Sasuke could just get over on his own. Like Sakura, Sasuke would have been a huge red flag to any other competent teacher and work to try to get through to him and if he still continued down his path, alert the Hokage and do whatever I could to get him pulled as a shinobi and get him psychological help if not have him committed or put under house arrest or something.