A couple of people I went to college with would not eat crustaceans at all. One of them explained his reasoning as "I don't eat bugs!"
Also, to the person who can't understand why some people eat bell peppers: My wife feels exactly the same way. She absolutely detests the aroma and flavor of them, and can tell when another piece of food has come in contact with one, even if only briefly. Unfortunately, I love bell peppers; but I can't even get them on half the pizza because the aroma grosses her out so much. (She claims they smell and taste like "spicy dirt".)
It seems that there are certain foods whose flavors are perceived very differently by different people; I imagine it is partly conditioned, and partly genetic. Cilantro is another one; some people apparently think it tastes like soap. I've also heard that Brussels sprouts taste like piss to many people (or at least, taste the way piss smells... I don't imagine many people have an actual basis for flavor comparison).
I happen to really like all of the above: crustaceans, bell peppers, cilantro and Brussels sprouts! Hmm... maybe even all of them together in a nice stir-fry!
Also, a fairly common flaw in beer is diacetyl (smells and tastes like butter, it is actually the chemical used to make artificial butter flavor). To some people it is glaringly obvious at parts-per-million levels, while others don't even notice it.