No one wants to see "Hannah's hookers" on their CC statement. It's a lot more likely to show up as "HH enterprises"

and no, it is most definitely not necessary for one to either incorporate or set up an LLC to open a merchant account, this goes for any business of course and not just hookers. There is very little reason for a provider to set up an LLC or to incorporate, as the primary reason to do so is for liability purposes, not tax purposes.

Most ladies I know, myself included, use something that's very generic or vague. For example, I make and sell things online so when I accept a CC payment it comes up with that name on the charge.