DragonsAteMyMarbles said:
I rarely spell words incorrectly, despite my frequent forays into the territory of the unnecessarily sesquipedalian.
(har har har, sorry)
This post made me squee a little. Or maybe a lot. ...Also, my own Internet spell-check thinks "sesquipedalian" is spelled wrong. Which it isn't. e_e
And that neatly illustrates why I tend to ignore it.

I'm pretty much a human spell-checker myself, so any errors are usually either typos I didn't catch or intentional misspellings for the lulz (omg i liek tu tpye lkie tihs!!) (ow, that hurt).
Tangent: Typos? Typoes? Argh, now I'm not sure which is right and it's driving me nuts. D:
Anyway, the main problem I usually run into is that I type fast, but not very accurately. So I make a lot of typos, but I correct them so quickly that I barely even notice. And my muscle memory likes to make me type words that I didn't mean to type (like, I'll try to type "jump", and my fingers will type "just" instead). Sometimes, just for fun, I like to type without correcting my mistakes; the results are invariably hilarious.