I would hate to have to fight a bunch of sexy naked women. I wouldn't find it especially distracting, I just hate the idea of making a world with LESS sexy naked women. It's one of the reasons I don't understand why young women are so disproportionately the victims of murder and other violent crime, don't the criminals have any sense of preserving great works?
As for rules for it, I think I would perhaps increase the crit range of everyone who was fighting them by 1 or 2, and make the non-naked fighters succeed on a sort of composure test (If they weren't immediately threatening I think a lot of combatants would struggle to justify attacking naked people). I think the composure test would be a will save vs. (10 + Cha Mod + Con Mod or the target's diplomacy check, if you want it to be a sexual thing remove the con mod for foes that don't fit the player's sexual preference). They aren't making an auto-seduction check, they're making a check to see if you count them as defenseless/harmful, or at least to see if you'd rather take prisoners than go for kills. A lot of times it isn't a sexual thing, but I think I'd have an easier time striking down naked dudes than I would have striking down naked women.
I think once you've made your first slash into naked flesh though, destroying its appeal, you really don't need to make another test to see if you can do it again. It's a lot less appealing now that it's bloody and missing some of the best parts. You see a sexy naked person who fits your sexual orientation and you think "Damn it would be shame to ruin that" but once you hit it with a sword your feelings probably switch to disgust very quickly and you'd like to make it stop writhing and moaning ASAP. No arguing for your character's fetishes because we aren't playing THAT game. I do like that BoEF introduces an appearance score though, saves me from using the con mod.
As for things like naked undead and other things that are clearly outside your racial category, they don't really get a check. A naked dead person coming at you is just as appalling as any other dead person coming at you, and if you don't see a creature as anything like you then you will not sympathize with it no matter its state of dress.
When it comes to Supernatural abilities and similar such things, I don't really see it as the same discussion. In addition to plenty of such rules being present in-game, their primary effect is ignoring any preferences player characters bring to the table.
