Possibilities near the Kempinski
Have stayed many nights at the Kempinski, but have also not seen any evidence of p4p there. The spa there seems legit, and mighty expensive. May be some talent at the Paulener bar (yes, the beer is expensive, but it is good! ). You might be better offstaying at the Traders hotel.
There are some places around there. Leaving the hotel, turn left and walk down the street along the canal. Make a left on the first street (about 100 m), which will be in front of the first of the row of high rise apts. Go down the street, about 200 m, and you'll find a place on the right side with the friendly glow of purple lights. If you get to the fruit stand at the intersection of the street with all the little restaurants, you went too far.
Did not sample the goods. Went in, the two girls there were 5-6s. But. One was busy massaging the feet of 2 young Chinese guys (I'd guess around 20. 25 yo dudes). One girl quoted me 200 RMB (but not sure for what, exactly). I left, not feeling at all comfortable about the situation with the boyfriends right outside the door.
I may have been missing something obvious, if so, would appreciate comments. Yes, I did RTFF, and there is not a lot of info here.
Also, crossing the big street in front of the Kempinski (opposite direction to above), there is another place tucked away in the first building, pink lights. Went in there, was quoted 500 by a well-past-expiration-date woman, so left there with nothing as well. Did a lot of walking around there, just didn't find much of anything.