Yeah, I'm kind of with you. I tend to sneeze a lot, including in class, and I don't see that someone saying, "bless you" draws any more attention to me than sneezing four times in a row already does. That said, while I do tend to say thank you, I...don't think I even notice if people say it back when I say "gesundheit." If people are getting snippy about that, the LW has a right to complain.

Otherwise, you know, feelings are feelings, reactions are reactions, but I wonder if the LW isn't focusing some of their frustration about their allergies on this. Having a kind of low-level misery about which very little can be done is, ya know, not fun, and it can often make what are intended as kind gestures annoying.