I only recall one incident as an adult when a work colleague sneered (and I really mean sneered) at the fact that I read Dan Brown (wasn't reading it at the time but I was discussing it with another and the snob said something like "... I did not expect you to read that rubbish...").
To paraphrase the other discussion in this Thread, it actually told me something about his character.
But it did not make me angry. Rather, I felt a bit of pity for him.
I'm inured to book snobbery anyway as, while growing up, I was constantly criticised by my father (and uncles and grandfather and their friends) for reading "novels" this being equated to a total waste of time and it was even thought that it somehow harmed me (nobody could explain to me how).
My problem now is that because I'm seen to read a lot, some people believe that I want to read anything and everything and they try to push their recommendations on me regardless of asking if these books are even in my favourite genres, etc.
And some, when I don't jump at the opportunity, seem to take offence...