I am not picky on the codes since I am lookin for plot as well as erotica.
I usually go by the the author's write up to see if I want to read it.
But incest, bestiality and snuff are real turn offs.
I clicked on a couple of those out of curiosity and confirmed my initial reaction. Nope, not for me.
I do read the M/f first, but will eventually look at some of the others.
If the story is well written, I'll enjoy it, even if its not a big turn on
for me personally.