I never had a problem with reading kink, slash, P(with or without)P, multiples, any of that. (Because I am a pervert. Or, rather, because I always was a pervert.) I came into fan fiction unable to bear:
- Bad spelling or grammar. If you can't use a spellchecker or (ideally) a beta reader, you're not ready to be writing fan fiction.
- Unadulterated sugar. Eternal bonds, the healing properties of penetration, proposals of lifelong unity between people who have hated each other for four books and had sex for the first time seventeen minutes ago, tears of joy because of the beauty and bliss and joy and oh, I love you of it all - you've got to be good to get away with that. As in, Shakespeare good. (And, as Chanson reminded me, we even roll our eyes at Shakespeare occasionally. See, for example, Romeo and Juliet.)
- Excessive angst. Look, yes, angst in its place is fine. Some fandoms were created for angst, anguish, and sorrow. But when you'd get less angst at an all-night poetry slam at a college town coffee house called Grounds for Despair, it's time to lighten up.
- Euphemisms. It's a penis, cock, dick, whatever. It is not a manhood (or a manroot), a loin (yes, I've seen this one used to mean penis), or a noble member (which sounds like the title of a British politician). Same applies to other body parts; call 'em medical names, call 'em dirty names, but don't use words invented by blushing censors. This is fan fiction, not a church social. Circuitous, flowery descriptions also fall under this category - if I'm not sure whether you're describing a sphincter or a new species of echinoderm, I'm not reading any further.
- Improbable or impossible sex. Anal sex between two men who have no experience, no lube, and no patience? Sex that requires both parties to have 18 years of yoga practice, knees of steel and teflon, and antigravity belts? These things do not lead to mind-blowing simultaneous orgasms; they lead to the emergency room. And the use of the Back button.
But my tolerance has expanded. My first six months of reading FF I think I bookmarked five stories. Now I bookmark that many some days. Partly that's because I've learned how to find 'em, but partly it's 'cause I can appreciate a story even if it's flawed. I can say, OK, I'm experiencing a sugar whiteout here, but I have never seen anyone describe the awkwardness of a first time so well. That's worth remembering.
Also, I've grown a lot more fandom-tolerant. I used to read very few fandoms. Now I'll read stories even if I don't know the canon (sometimes this works - hello, Sentinel slash - and sometimes it doesn't - goodbye, Buffy slash). I'll read stories I thought sounded downright sacrilegious this time last year. (Most notable example to date: Summer's Men, by Kest. This is Dark Is Rising slash, folks (Will/Bran). Even six months ago I would've gagged at this, and two years ago I would've been ready to call out the villagers with the torches and pitchforks, but last week I actually read it. And it's good. The concept is beyond redemption, but the story redeems itself nonetheless.)
So for me, at least, it's not exactly that fan fiction corrupts (though I'm not saying it doesn't); it just pushes my limits a bit. Some boundaries hold firm (I've never found a story with lots of spelling errors that was still readable, for example), but some turn out to be unnecessary.
Hey, I think I just worked this around to the point where I could argue that fan fiction is noble and ennobling. Seems like I'd better stop while I'm still in the right universe.