Pretty simple.
For example, I really really want to like mushrooms. I like just about every other staple of Italian cooking I can think of, but I cannot get past the texture of mushrooms no matter how many times I try and no matter how many different ways I cook them.
Cauliflower also. It's not so much that I want to like cauliflower but it gets thrown into so many veggie mixes that it becomes hard to avoid, and it ruins everything it touches.