What is defined as 'normal' is a difficult concept to pin down. In the strict sense of the word, the 'norm' means practicing things which are done by the majority, but in modern language, the term 'normal' has other conotations - as in your question. So, in the strict meaning of the word, your boyfriend's minority taste is not 'normal' but it is not uncommon. If he enjoys it, and you don;t mind, I wouldn't worry too much - after all, it's not like you're going to take a straw poll among your friends is it? The least he can do is stump up for some new shoes and nail varnish on a regular basis!