If it's with gil, not really anything you can do except add them to one's blacklist. Personally, I don't see an issue with it, but I understand that others feel differently. If it's for RMT...they are vague listings on purpose to catch someone's interest enough for them to have a look at their discord link. So to me it's a no brainer, but from a GM's perspective following the ToS it's hard for them to prove since none of it takes place in game.