It's fairly common practice for girls to create AW profiles as well. As long as they're organised splitting their time between clients on there, and their time with the agency, and aren't doing back-to-back bookings it's not an issue for me.
However, yes, if there's an increase in price, it doesn't exactly make me enthusiastic to see them. Even if she charges £50, she's still making more money independently since the agency would otherwise take a cut. The first thought is pure greed, which goes hand in hand with a crap attitude, taking guys for idiots. Or maybe it's not the case, I don't know how much it is for an escort to have a profile on AW, so maybe it's to cover fees?
On the plus side, the profile will give you an idea of likes/dislikes, and maybe pics that aren't photoshopped.