yuppie is right, although hatrick and a few other seasoned street cruisers would disagree
police street stings take three forms
1) this is the most common form. an escort-disguised policewoman standing on the street seeking solicitations from you. if they are going to make the charges stick they have to prove a few things. the judge will rely on the woman's testimony about the nature of the conversation. however, he requires independent testimony that you actually conversed with her at all. you can do two things to avoid this type of sting. you refuse to indicate that you are looking for sex when you first talk to her, instead asking her in a completely neutral manner if she wants a ride somewhere else than where she is standing. she will of course refuse to do so as that would take her out of the range of observation of her back-up team, something they will never do. if she refuses you say 'ok, if your not looking for a ride, sorry to have bothered you. have a nice evening.' and go
this is even better done on foot as it is more difficult to prove that a private conversation between two people is 'communicating in a public place' whereas from a car that is arguably obstructing traffic, it is a much easier thing to prove
2) the police will intimidate a street walker into acting as bait then swoop out of the nearest dumpster

and harass you. in that case you tell them that you were offering the woman a ride to the nearest macdonald's to buy her a cup of coffee and a big mac. if they say you are in the company of a known prostitute you say 'what? she looks like an unfortunate person in need of a ride and a meal to me.' they won't like it but a judge can't rely on the word of a civilian so after a long lecture and a car search and a lengthy examination of your id and car they will have to let you go
3) the police will be patrolling in an umarked and observe you pull over and swoop in on you and harass you. for your reaction in this case see 2) above
if you don't think you have the nerve to carry it off politely, don't cruise the streets. if your living situation can't withstand letters from the police telling you that due to you being stopped in the vicinity of xxx street and yyy avenue in the company of an unidentified female on april zz, 2013, don't cruise the streets. it's just that simple
massage parlours require a licence from the city to run the business. police drop by on rare occasions to make sure the licencing provisions are being observed. sucks to be you if you're getting a massage at the time, but basically except for the delays inherent in answering questions about the service you were getting you will be let go after questioning
micros are run illegally out of houses or condos in residential areas. they usually do a good job of keeping under the radar, but rarely the triads that run them get into a bit of a pissing contest and turn the competion in to the police. police will raid the joint and check for illegal workers and again harass you the customer. expect the questioning to be rather lengthier than a raid at a massage parlour, but again coolness in the face of police questioning will usually get you off with a lecture
good luck