I think there are plenty of good points on here, and in a way it all reverts back to the usual problem.
Why is it that when a story contains "taboo" (please note heavy use of "_" in there) material for valid, plot driven, non titillating reasons, it is either quietly sidelined or actively dismissed?
and i think Thorn is right, if anything mutual sexual exploratory activity between pre-teens is possibly the only thing worse received in this community than incest. However, i think i might have worked out the reasons for this...
i used to post on StoriesOnline (SOL), a sexually explicit website where everything goes, and i mean everything. stories involving any age, any gender or combination of genders and species, etc etc. however there is an extensive list of codes as a checlist system, and you can check as many as apply to your story. it was the only place where i never recieved any of those "this is disgusting and wrong" type reviews because you knew exactly where you were going in. if the tags said vore and you don't like vore, you just don't read. the mod's are incredibly hot on coding-errors and read everything before it is posted. every story is moderated before it goes live to make sure the author is using the correct coding.
Because on GA we have to chose just six tags from a rather big list, and people don't always read them, they get into things they don't like without realising it. at that point, human embarrassment just makes you click away without saying anything to the author at all. While i understand that GA does not need anything like as overarching a system as SOL does, maybe we should try and use the codes to better affect generally as currently they are rather sidelined.