Spell checking math, and in particular LaTeX math, is a complete nightmare. I, for one, find that there are just as many substantive typographical errors after spell checking my papers as before, and all I've done is wasted at a minimum an hour trawling through false positives.

Besides, small typos in a paper that's substantially readable and well crafted, written by someone in a language other than their first, are scarcely a reason to stop reading.