I write , on occasion. Debating posting a story on here, but if i did, i would probably make an actual account instead of logging in with FB (like i am now)
I like stories that have correctly spelled words, and no missing words in a sentence. 
It is always a shame to find an awesome story, but it's riddled with typos, missing words, and incorrect words ( IE: wrong usage of the 'their', 'there', they're ) etc.
It seriously makes my brain twitch..and not in a good way. I sometimes can't finish a story because of it. lol
But others, the story is so good i force myself to suffer through it, cringing all the way,, because it has the potential to be so excellent, but people don't even bother to put their stories through spellcheck before posting it. I never understand why. 
anyway, not trying to be mean about that...just confused? and it's a huge pet peeve.
I only recently started reading Fanfic, and I love it when people actually stick to how the character really talks and such. huge bonus points for that!