Can Anime Fan-service Be A Bad Thing?

hmmmmm
lets imagine for a moment

Sometimes. I'm not a fan of that kind of thing, but I won't stop watching if it does have some fan-service. However, if it shoves the fan-service down your throat, then it gets annoying.

Yes, especially gay boy fanservice just to serve fetishistic yaoi fangirls instead of producing a healthy and realistic gay relationship.

If it's something like a crossover episode, then no.