wit's end, people are not saying that their parents' deserve visa; they are frustrated because they are being rejected without any valid reason, multiple times. if you were on the same boat, you too would be throwing crap at US Embassy. so, stop your bs and get the hell outta here if you can't contribute anything.

sp123: haven't faced situation like yours yet, but i'll be on your shoes in a few months. situation is scary myaan, don't know what the hell is wrong with the Embassy. i'm teaching myself this - if they get visa, that'd be really nice as they'll get chance to see me graduate and see what's America like. if not, oh well...
re-applying might help, but as other's have pointed out, it's pretty random. 
good luck!