A commenter on another post made an important remark which I think is worth promoting (I edit because I don't want to single out that particular teacher in what I'm about to say. I don't think I am misrepresenting the comment in any way):
"... as a result of ... harsh(ish) style and poor(ish) reviews the thin skinned stay away ... If you don’t want any meaningful feedback go to a handful of other classes where the teachers are kind and smile and say “so much better” all the time."
I agree with the need for meaningful feedback. This is important in a teacher. But personally, I prefer above all a teacher who knows what good dancing is, can dance well, has carefully thought through, worked on, and tested their approach to teaching, and treats the students like intelligent adults. Criticism and praise are useful tools in as far as they help achieve results. Good advice is much more important than either.
In my opinion, someone who cannot give useful feedback while being courteous to other people and making efforts to put them at ease is by that fact poorly qualified to teach anything to anyone, but least of all social tango, a broad skill-set of which good manners and behaviour are an indispensable part. And no qualification of any kind excuses poor results.
Bottom line: if you care about results, it is your responsibility to make them happen - by choosing your teacher, among other things. If you don't care about content or results, you can freely indulge any preference you have as to the box it comes in. Such things are widely available at very reasonable fees.