Couple of things I do with dialogue
1. Very often, I will have a character go on a rant. And I mean like a rant. Probably about 100-200 words, and this isn't a rarity in my writing. It's usually for a purpose, or to demonstrate a long thought process, but I do this more than I should.
2. I often have just entire scenes consisting almost completely of only dialogue. Like, sometimes there will be an 800-1000 word scene of nothing more than dialogue. No descriptions, no narration. Just two people talking. I try to avoid this for the most part though, and actually describe the surroundings, actions, and reactions of the people when they're talking.
Furthermore, I suck at spelling. Yeah.
Oh, and also- I'm lazy.
Often I have to look back in my story to check whether something is one way or the other, and instead of searching for which chapter I wrote it in, I instead just say ok lets forget about it and just make it vague so that it's right either way.