The thing about rudeness is the fact that it's relative just like many other things. While I find it rude not to thank the one who corrected my notebook entry (or not to be thanked for taking the time to correct someone's entry), others may just find it normal and ok.
Since I've never looked for a language partner before and usually study on my own and take language lessons whenever I can, it happened to me once that my teacher simply yelled at my face all of a sudden when I asked her to start with something in my class before the other thing. What I asked for wasn't going to ruin what she had prepared for me in any way, but I was simply yelled at and told that (no, this is not possible and stick to the way I prepared things). My face became in colours mostly green like Kermit because I was shocked for the way she reacted and I wasn't really sure where I went wrong. I only asked nicely! It was even a suggestion and since it was my 1 on 1 class, I didn't really think of it as weird to ask for what I want. I gathered myself that day and continued the class normally as if nothing happened.
Told myself I would give her another chance (because it's possible that she was having a bad day) but it happened again!
I don't usually stay quiet in these situations but she was old and I just couldn't break that cultural thing we have about treating the old people nicely no matter what. So I kept quiet and thanked her as I normally do but never booked any class with her after that.
The way people of my target languages behave would never change my idea about the language itself and I would definitely stick to learning it. The only action I would take is staying away from these individuals and avoid them like the plague :D