"In this fandom, I've requested Harry & Draco. I don't ship them - I ship Harry/Hermione, Harry/Ginny, and Draco/Luna. If you're writing shippy fic, please only those three ships. :)"
"In this fandom, I only really ship the canon ships. Thanks!"
"If you're a porn writer, I would love to read porn for Snape/McGonagall, Luna/Dean, and Colin/Parvati. Other ships are fine, but I'm only into explicit fic for those pairings, sorry."
Etc.
Sure, there's no easy way to say "I'm not a homophobe, but please don't write me slash or femslash." You have to use your words.
Re: Letter judging post again
"In this fandom, I've requested Harry & Draco. I don't ship them - I ship Harry/Hermione, Harry/Ginny, and Draco/Luna. If you're writing shippy fic, please only those three ships. :)"
"In this fandom, I only really ship the canon ships. Thanks!"
"If you're a porn writer, I would love to read porn for Snape/McGonagall, Luna/Dean, and Colin/Parvati. Other ships are fine, but I'm only into explicit fic for those pairings, sorry."
Etc.
Sure, there's no easy way to say "I'm not a homophobe, but please don't write me slash or femslash." You have to use your words.