Count me in on the licorice hate. I truly, just truly from the depths of my soul, despise the taste.
Usually though for me it is about texture not flavor. I like most flavors. Some textures send my OCD into overdrive. My biggest trigger? Gristle in meats. As such, one thing I will never, ever, EVER eat is a cheap hotdog. Those little bubbles of pure fat in it.. biting down into them and it being like... just a hard white chunk in the middle of the meat... Oh jesus I am seriously physically ill just thinking about it. Same thing for cheap burgers made with high fat meat. No, no, no, no, no, no.