The reflection staring back at shoppers in a dressing room mirror can often leave them scratching their heads.
Ana Valentin trusts her bedroom mirror a whole lot more than any she faces in a store's dressing room.
"You get in there and it's like you look wider - or maybe even smaller than you are. And it's like, what is happening?"
What is happening is a sort of mirror manipulation.
Experts like shopping scientist Paco Underhill call them "skinny mirrors".
"You can subtly adjust a mirror to make… if you are a size 10, to make you look like a size 8. It's a matter of the curvature of the glass."
He says tilting designed to alter our reflection...and perception. "Tilting is one of the tools people use to make sure you look as good as you possibly can.
Underhill showed us the VIP dressing room at Club Monaco's flagship store in New York.
He says the room was designed to make shoppers feel comfortable and look their best.
I decided to visit about 20 other dressing rooms and there were significant differences from one mirror the next.
But Underhill says good lighting and a little tilting can make all the difference.
Ana says her contradicting fitting room figures are frustrating.
"So often I have this battle face on to go into the dressing room to make sure that I'm not talking down to myself because of the lighting or the mirror or whatever it is."
To get a true reflection she tries new clothes on at home and then returns what she doesn't want.
Paco Underhill also says the average time we spend in dressing rooms is increasing.