Here's a question, though: how do you determine what is potentially questionable material that you should ask about? Look upthread for an example: one anon thinks rimming isn't a particularly big deal; another does. It seems likely that one of them would consider asking about it while the other wouldn't think it needed to be mentioned.

On a kink meme, there is such a wide range of possibilities, that I do think you go into prompting knowing that you are taking a risk that someone might take the fic in a direction you don't want. Should every filler have to list every single thing they are planning for the fic and get the prompter's permission first? That seems a little extreme. If the prompter has definite DNWs, bring them up of course.