Recently watching Kill la Kill has got me to think about this a little bit. I've seen varying opinions on the subject, some think it's a pleasant and welcome inclusion, some believe it can ruin a show or video game completely for them, and of course, some are indifferent towards it. It's pretty ambiguous, and although I can guess what the most common opinion might be here, there are likely to be varied answers.
For the sake of avoiding "If it's rare and infrequent then I don't care" answers, let's make this about works that are well-known for noticeable amounts of fanservice. Is there a point where a significant amount of it can cross the line? And if so, what are some examples in which you feel that is the case? Any examples of tasteful fanservice that you don't have a problem with at all, and that may actually improve the work in some way?
Edit: I was mainly thinking of sixual fanservice. My mistake for not clarifying. That's what happens when my only definition of fanservice comes from TV Tropes.