It depends. For instance, if you're going to the movies mostly to see a werewolf disrobing every other scene, then sure -- job well done. Or you've got a fetish for giant robots and explosions, then who am I to complain when it's delivered in spades? Anime/manga series usually start in the ecchi/moe grotto, occasionally more modest series become increasingly sexualized, but mostly the boing element is obvious within the opening credits for the first episode. The same can be said for most of all the other aesthetic fetishes -- from shounen-ai to mecha. They may be one tracked in their need to please their niche viewers, but they're typically honest about it.

Smallville's Erica Durance became more stripperific as life went on, far more than the tame Kristin Kreuk as the lead female role. Natalie Portman went from vaguely ethnic virgin queen in the Phantom Menace, to slutty-looking senator in the Clone Wars, dialed all the way back to nun in the Revenge of the Sith. Leia may have worn a chainmail bikini, but that was under duress -- Carrie Fisher was pretty sensibly dressed for the rest of the series. In either case, it just felt awkward -- the product of a bunch of men looking at ratings and focus-groups and then deciding this week Lois is going 20% more nude and 15% more Tsundere.

Sexual fan-service is probably the most egregious in fantasy and urban fantasy literature. I can't tell you the number of times I've rolled my eyes at the immature wish-fulfillment forced into narratives. I don't know if that's technically "fan-service" or simply the authors' doing whatever the hell they want, but I've sworn never to read another rape scene for as long as I live.

Still, the fan-service I loath isn't sexual in nature, it's when authors take their cues from the fandom. This is why actually killing superheroes or characters from a shounen battle-manga is damn near impossible, and the tension simply evaporates regardless of the situation. True, that most stories of these kinds have heroes who ultimately succeed through adversity and you shouldn't be surprised when good triumphs over evil, but it's another thing altogether to know all will be predictably be back to a convenient stasis so long as a character has an ounce of name recognition. I find the lack of willingness to follow through on what could be dramatic and compelling narratives out of fear of fan reprisals -- is really, really, really annoying.