What a great question. In the early stages of a story I'll spend some time describing clothes as I think it's important to get an idea of who the character is and how they present themselves. But as the story goes on I'll just occasionally say things like 'she wore her usual ripped jeans and T-shirt combo' or something. The only other time I'll describe the clothing in detail is if it is part of a scene to come. So if a woman is going to do a striptease for a guy then obviously the clothes become an important part of the narrative. How often you describe clothes is a difficult one to manage though. With Chekov's gun in mind, after the initial presentation of a character early in a story, I find that it's best to either describe clothes all the time or not at all. If you suddenly describe someone's clothing in detail where you haven't done so before the reader will come to think that you've done so for a reason, and if the reason does not appear in the story they'll feel cheated somehow.
With Chekhov's Gun in mind, if you usually don't describe the clothing but suddenly do, it should serve a purpose. The obvious choice might be that it will be taken off to have naughty times. But another purpose might be to show that a character lusts after another character due to or despite the choice of clothes but don't get their fantasies fulfilled either way. If the purpose is always the former, a story might become pretty predictable and in my opinion that's rather boring.
If the characters go straight from fully clothed to undressed before the sex scene starts, then describing the clothes may not be as necessary (unless the writer believes the clothes tell something about the person wearing them that the reader may value.) But if there is a slower tease or clothed sex then at least some things need to be mentioned.
