That’s a tricky one… Frustratingly, I’d have to say it’s on a case-by-case basis. So much of non-sex fetish is… so particular that it’s hard to place.
Like, the blueberry scene from Willy Wonka was originally intended as child-safe body horror, but it’s become one of the tent-pole fetishes.
I guess I’d say as a guideline that if the intent of the content is to tittilate and arouse the reader/player then it should go into NSFW.