There was a recent thread about this. https://discuss.clearancejobsblog.com/t/soliciting-prostitutes-is-a-no-no-for-clearance-holders/16309/1. FWIW, Marko does claim it’s not acceptable. However, he also claims it is against the law, which it is not. So just take that warning with a grain of salt.
Technically, there is no federal law prohibiting prostitution. If you go to the red light district in NV (where it is legal), that in itself should not cause issues. The issues come up if you feel any guilt or do something that could make you vulnerable to blackmail.