Oh, that can be the worst feeling (as far as I've experienced, as I've never received active hate - only been ignored)! Zero response happened to me (for instance) at the first fests I did after a long hiatus (at a fest that wasn't an exchange and then when I wrote treats). Behaviour at fests seems to have changed in this way: giftees don't always comment. What's important is that we keep writing and it keeps us happy, and we can find some friendly corners in fandom!