Follow up question : Given the target audience (dudes mostly), why should they help you rather than purposely misguide you into choosing the worst ones in order to undercut competition? A bit twisted I know but hey, if I thought of it, I'm probably not the only one ;)
I've posted this on Product Hunt and Reddit this week, and so far people did 33426 votes on pictures. Pretty crazy!
Interestingly, a few comments (yours and on Reddit) assume how "bad" people can be. Surprisingly, so far, overall voting behaviour been very positive. People have not been abusing votes, comments nor images in the past few days.
So far 170 users uploaded 218 photo pairs - and all of them are genuinely good.