A comment that agrees with your post, yet the hit is negative... Now I have got more than one of these. Although there wasn't much of an impact with either, it still begs the question whether the "I approve" and "I disapprove" aren't quite clear to all people. Maybe somebody thinks it doesn't mean you judge the post, but it's used to either approve or disapprove the greater matter that was being addressed in the post? And so if your post was a negative answer to something, the "I disapprove" would be agreeing with you by also being negative..?
On the other hand, maybe they were just ironic comments that were lost on me (irony rarely works over the Internet, as everybody should know. With almost no exception it's taken as hostile sarcasm).