Manscape yer cacknballz. Chick don't want a dental floss when they're shuckin' cack. Also, keep yer sack clean. You may stink bad and denying bj's is her way of telling you that. If she really is self conscious about it, use positive reinforcement. Heap praise on her abilities, and gently offer advice for better performance. Be more of a coach.
I have a few other suggestions, but they're probably against the law in your region.