Though it's rather inappropriate for what the auction is intending to sell, she is not 13 at all.
What's sad is I can't really tell if she's 18, 19, or even 20 and I'm 21. It's even hard for me to figure out who's 18 these days as a lot of teens wear the same stuff I'd expect to see college girls wearing down at the clubs on a Friday night.
As for the comments about having back problems, yes she will unless she gets a reduction. I knew a girl comparable to the one shown in the auction who ended up needing it done because of a doctor's order to do so...It was a sad day for all.
(I'm 21 so it's not too inappropriate to say such things.)