I'd probably be classed as a fussy eater - tastes are very simplistic/childish, I'd much rather have fish fingers and mash than anything with a sauce on it.
I don't like curry, don't like many veg (I'm a fiend for peas and sweetcorn though), hate baked beans, don't like eggs other than the occasional boiled egg and soldiers if I'm in the mood, don't like things with sauces I've tried on it other than ketchup and BBQ (I even hate brown sauce).
I don't know if I'm more sensitive to horrible tastes or other people are less sensitive, or if it's something to do with stomach issues in the past, but I can't just grin and bear it and eat it, say 'Ooh yummy' or whatever. I think it's much more polite to silently leave it on the plate, rather than to force it down and be sick, which is a very real possible alternative, particularly in the case of beans, eggs or celery.
I politely refuse, or just leave it and apologise if questioned on it. People who question it or make comments are rude and annoying, IMO. Those who 'perform' their fussiness are rude and annoying too, but if you get genuinely irritated at people for disliking/being unable to stomach the same foods you like, you're the one with the issue to be honest.