I’ve seen this happen. It just appears that most teacher’s magically become super helpful and bubbly when and only when there’s a peer watching. Quite weird sometimes to be honest.
Says alot about that teacher then, doesn't it?
I get that teachers do that, but from my own experiences everything gets looked at... from whether the teacher is following the teaching model the school has, how students enter, how students interact in the lesson, what types of activities are used etc. It is much more than just 'can the teacher engage and be bubbly'.
From the student point of view it is very tough to see the amount of scrutiny a teacher gets. While it may not look like much is done, there is (because most is done so behind the scenes). Of course the process isn't perfect and some get through being extremely sub-par, and if that is the case I would encourage you to speak to somebody about it so it can be rectified. If you are genuinely curious, ask your teacher or better yet, become one and see for yourself