Let's see:
Avocado for starters. I used to like it, but after having a sub with avocado and getting a bit too full, then walking around in 100 degree weather for about an hour and getting sick, then proceeding to vomit for the first time in years, I ceased to like it, and now I find the very thought of avocado to be nauseating. It's a shame, considering that my love for it was short-lived, as I had only just had it for the first time maybe a month or so before that happened.
Tuna Salad/Chicken Salad/ Cole-slaw. Yeah, I haven't really had much of any of them, but I didn't like them when I had them, and they all look like chunky barf to me, so although I can't actually criticize their taste, I just have no desire to try them at all.
American Cheese/Vienna Sausages. Both things that my dad described to me in such a way that it made me become absolutely disgusted with.
Asparagus. Well, there's an exception for this. If it is sauteed well enough, then I might actually even enjoy it, but plain, it just has a horribly unpalatable bite to it that makes it difficult to eat.
Also, cumin I think it is, that seasoning that is in Italian sausages or something like that, I hate that taste so much, and it ruins whatever it comes in contact with for me.
That's about it I think. Oddly enough, I'm game for more less desirable foods like brains/intestines, or foods from animals we don't normally eat though.
Edit!: OH, and bell peppers. I don't refuse to eat them, and can eat them, but I hate their taste and they add nothing good to whatever they are added to for me. And I hate BBQ sauce now too. I used to like it, but came to dislike it.