I've purchased handicapped seats when a friend of mine was late making it to the ball game. I met him and went in with him, so I don't know how aggressively the ushers give you a look if you are there with someone who does not have a obvious access impairment.
So...I just realized the tickets I bought off stubhub are ADA seats a little while ago (section 235 Row P). I must have missed it when I was buying them or something, but I don't use a wheelchair or anything, and neither does the guy going with me. Does this mean I'm screwed basically or what?