I keep seeing videos on youtube of people complaining about "too much fan service." Personally I love fan service, I can't get enough of it, I don't believe in too much of a good thing.
There is no such thing as "Too much beer," or "Too many naked Japanese schoolgirls."
The animes that are accused of having "too much fan service," High School of the Dead, Agent Aika, should have a lot of fan service. They're the equivalent of drive in exploitation movies, they're supposed to be big dumb fun.
If Studio Ghibli was inserting random cleavage and panty shots, fine that would be distracting. But things like High School of the Dead should have copious amounts of fan service, it fit the tone of the show.