It's not so much the picture in my experience, as the actual girl. How many times have I been attracted by a picture, only to meet the girl who, well, you know, looks nothing like it. One lovely pic was of a voluptuous blonde, who turned out to be a skinny brunette.
"I've died my hair and lost some weight," she said.
"Yeah, right, I said ... I almost added: "Your ugly now, too!"