Fake boobs and pussies

I still don't get it, why on earth do some users, who otherwise seem real, upload pics of random genitals from other porn/file-sharing sites?
Why do people do that, is it only revenge-profiles made by "friends" using private pics, or do they feel too curvy or something? For me personally, it's a major turn-off, I'd rather see a curvy arse that doesn't show up a dozen times if you image-search it.
Please comment if you know anyone who has done this (or in case you want to confess!).