"Thank you" is a social nicety said at the end -- indeed, one cuts a bad tanda short with "thank you." So I agree not all thanks are genuine in terms of deep appreciation, but arguably sincere in the sense of being nice, "thanks for the effort", and similar. Also, I think all involved realize its a social grace thing and not a Deep Truth kind of thing.
I think many approach compliments with a different view. Here are some counterpoints:
- Usually there is something to compliment, it's pretty rare someone is 100% bad!
- Many (actually almost all) of us scale our compliments against that particular person. If a youngster shows me how fractions work, they get a heap of praise. If my chief scientist did that, I'd call his wife with worries about his mental health! If a newbie does a double-time step, or 2 steps in a row with the same foot, that is something I'll compliment. It is a higher threshold for more experienced people.
- I've heard complimenting something specific is better than a more vague compliment. Getting granular like that with compliments enables more fresh compliments, and more ability to pick out something good from a less perfect dancer. It also helps the compliment be sincere! "I like how I can lead you to take a big step into me!" (Said while while pointing and stepping back with a foot to show.)
- Yeah, someone might compliment hoping to get more dances, but that doesn't necessarily make it insincere. That is part of my dear wife's success. She tries to compliment every tanda, and says there is almost always something you can compliment.
- My tango distance journey showed me Tango has many truly kind and wonderful women (and I'm sure men, just don't interact as much with them). I'm sure many compliments are a natural product from a loving and kind person.
I'd love to heard others thoughts on compliments on nondance things. One older lady wears really nice dresses, and I compliment that. She said "You are smart, this is why you are still married!" I don't do this with younger ladies, but it seems appreciated by the older ladies (maybe the younger ones would, too, call me risk adverse).