i've played with nisa's wicked perversions for a while now and this happens ever time. sims with the sensually tight trait get tears after having sex, but the ones around their mouth dont come off like the rest of the tears once the buff expires. so far the only way i've found to fix this is to remove the files from the mods folder, run the save, and then add it back. i couldn't find any other way to contact nisa, since there's no link to anything on the page and she only says to create a forum.