I'm a snowballer. For me, as mentioned above, its about sharing an intimate, and slightly taboo moment. I can;t say I relish the taste, but It's not offensive. I prefer a DFK type exchange to a mouth-to-mouth dribble.
Apparently a lot of guys who ask the girl to do it, bottle out after they've cum. Many new girls I've seen do a sort of hummed "you still want this?" while pointing to their mouth. When you've seen them before and they know you're not going to back out they get on with it
If the idea does nothing for you, I suggest you don't do it. if you're curious, give it a go and just commit to it.