I can almost see the "I'm allergic to apples!" response as something like "I'm bummed I can't ask about the recipe from you, because I'm allergic to apples!" But there is no excuse for just posting "Yuck!" in response to someone else. One of my friends is vegan, and we will occasionally post responses to each other's food things with faux-outrage, but never, ever would either of us dream of disparaging the other's food choices with "Yuck!"
My little annoying thing is the cousin who is constantly posting FB glurge about how family is the most important thing. Yes, the same cousin who has managed to not ever visit any of us in the last 20 years, and prioritizes trips with "her girlfriends!" to a spa or Disneyland over her grandmother's 80th birthday or her aunt's 65th birthday celebrations. Yes, the same cousin who has never manages to even send us Christmas cards or her kids' school pictures despite all of us showering her kids with holiday gifts and her family with cards. The same cousin who cried at Grandma's funeral about how much she misses all of us and we need to visit more, but then didn't return any of our phone calls or emails offering to visit. But I guess posting something cute and inspirational on FB trumps one's actual *actions*.