It's nice when your mispelt keyword has the ad showing in glorious isolation but how long is it before it's added to broad match. Presumably this is based on the number of clicks?
I know that my ads show on misspelled words that I did not specify in my campaign. So I'm speculating they do use some kind of algo to figure out what is a probable match for misspellings. I also notice this for my competitors' ads.
It's good to track which keywords are driving clicks that you aren't bidding on... especially the mispellings. Some companies have been seriously burned over this. Anyway, thats what negative keywords are for