why do i sometimes accuse non "en es eff double-u" posts of being "en es eff double-u"?

had to spell it like that to avoid me having to manually change the tag to SFW, but i seriously don't know why, whenever i see a post that seems very adult without the 18+ tag applied, i assume that it is 18+, but then in reality it isn't. how do i stop myself from thinking this way?