Putting together a few different poster's potential ideas...Perhaps she wore gloves during the murder but took them off when she went to wash herself in the shower where she had dragged TA already.. and lost her balance, because she was standing between TA's body and since she couldn't catch herself with her feet because there was no room to step, she had to catch herself with her bloodied palm.. JUST an idea, putting it out there.. That may be why the print is in the shower, why her prints aren't elsewhere and how she got cleaned.
It is really gruesome to think if this is premeditated (which I believe thus far it entirely was) that she had sex with this man that day and in her mind she knew she was going to be killing him shortly thereafter.. Just very sick! I think that shows, to me, that she did NOT think of sex as something meaningful at all besides a method to her personal gain. And to me, that means every sex act she performed wouldn't have made her feel like a prostitute or used because she didn't put any special or "sacred" value in sex.