This is the "complaint" I read most often. For some reason, there's a rumour that it was originally an adult show. Some people add to that that Spongebob and Patrick were supposed to be a gay couple, or that it started out airing on an adult network etc. I'm not quite sure why people think this; basically it's just a rumour that goes round and round parenting forums but nobody debunks it/breaks the chain; therefore, more people accept it as true and bring it up at the next "Spongebob debate" (of which there are hundreds).