Omg! Giving head is actually my favorite thing to do for a guy. I have never had a complaint yet, and no it not gross or dirty (as long as they have good hygien as several people have mentioned). If you have a problem with it at first then just start out with a handjob and give the head a few kisses and then gradually graduate to licking the tip and the shaft. My guess is that once you hear his moans of pleasure you'll begin to enjoy it or at the very least not completely hate it. And as several people have said already, you can get in the 69 position (you on top) and you'll get some pleasure as well, which will probably enhance your liking of giving head.