I really don't mind when the coincidence feels natural, but you can tell when it's forced, I hate, no, despise that. I mean, we're already suspending reality just watching anime, and some exaggeration is expected, if not demanded. There's really no reason to force an exaggeration though. Especially, when it comes to fan service or nudity.
Like, I remember reading the manga...crap, I forgot the name, about a boy who wants to loose his facade, and the girl wants to stop wearing her heart on her sleeve, makes a wish at the Stony Cat or something?, and the other popular girl who's into pet strories.... (*goes off to google it*) anyway, the girl is in the process of changing or showering or something, and the boy, not paying attention accidentally walks in on her. That was funny. But, then if I look at Negima!, when Negi sneezes and literally blows off Asuna's clothes, yes, it was funny, I guess, but it felt over the top forced. Giving a panty shot would have felt more natural and had been funny.
Maybe I'm just getting too old to enjoy perverted humor?