Well first you shouldn't have to do something you don't like and as for the part where you say you don't know where's it's been....should also apply to the fact you're about to stick it somewhere else too. Listen if that's what's stopping you then use a flavored condom for head. And regular condom for penetration. Come on kids. But like I said you should have to give head if you don't like it. There's other kinds of foreplay which is very important in any type of sexual relationship, meaning casual or relationship.