Hi Vince! First of all, thanks for requesting me. I'm going to do my best to answer your question.
You have to realize, I'm sure, that no undercover cop posing as a hooker is going to admit to you that she's a cop. Not until she slaps the cuffs on you, anyway. The very essence of police undercover work is to fool you into thinking they are not cops. You could approach a hooker and ask her to swear on a Bible that you whip out of your pocket that she's not an undercover cop, and she could swear on it twice, and still arrest you as soon as you solicit her for sex.
That's their job, Vince. They are a worm wiggling on a hook, and you are a fish. She'll swear she's just an ordinary worm, and the next thing you know, you're flopping around on the bottom of a boat with a hook in your mouth.
Didn't you read the papers about New York's governor Elliot Spitzer? He got caught going all the way to D.C. for sessions with a high priced, $4500 an hour callgirl, and he still got caught. He thought that at those fancy prices he was buying security. He resigned in disgrace just last month.
There's no safe way, Vince. If you want meaningless sex, try the adult 'friend' websites. From what I hear, there are plenty of women looking for short-term, no-committment hookups.