My experience is primarily with the Craigslist pages between Modesto, CA (to the south) and Seattle (to the north) and on the I-5 corridor. My focus was strongest on the Sacramento area which was quite the hotbed. The FBI agent told me that all classes of men use the services. Here's what I know to be true (however, it is just my observation):
Almost every ad included a photo of the woman
Some photos were professional, and marked as such, but the vast majority were taken by the woman herself in a hotel bathroom (from the appearance of the bathrooms, I would gauge the motels to be mid-to upper-range/motel suites) or on a bed in a motel room. Very few looked to be taken at a private home.
I've been told that the "amateurish" photo is done on purpose as the pimps want the johns to think that the women are independent. Rarely is a pimp's name in a tattoo shown in a photo. But almost all women are forced to get the tattoo so that the pimp can "claim" them.
Items on the bathroom counter signify what sorts of services are available. A container of vaseline is common if the woman's services include anal sex
Prices were outlined by the 15 minute increment and many women also provide "car dates"
Measurements and age were prominent
"Just starting out" or "just turned 18" typically means they are underaged
Women of absolutely every color, size, shape and age are available. I've seen numerous ads for women in their 50s and for women who are 9 months pregnant or lactating. There are many many typically attractive women but I was surprised by the number of women who were extremely unique--either pregnant, older, very obese, with unusually large breasts or bottom, thick and muscular thighs, or very boyish or young looking.
I was told that the pimps control the cell phones, cameras and laptops. They write the ads. A phone number was usually "coded" and written as "five-0-three-fourteen-1-1-3 hundred" so LE could not run a check on the phone numbers via a simple search of CL. Callers were warned that anyone with caller ID would not be answered. Callers were also warned that no profanity would be allowed during phone calls.
The same photos would show up under multiple names, which change as the women are moved around, usually every few days. The word "visiting" means that the group is just passing through and not local.
I was told that most women were kept in groups of 3-10 and managed by two to three men. One is the pimp and the others are the drivers. A woman never drives herself, she is driven to an outcall and taken to the door, where the john hands over the money. Almost always, the cost has increased by the time the woman arrives. The driver stays outside but will call or knock on the door when the time is up. At that point, extra services can be arranged. The money is never in the hand of the woman.
When the women are initially procured, their IDs and personal effects are taken away. Drinking and drug use is not allowed so there is no need of an ID. The pimp provides any medication he deems necessary. He also provides the condoms, sex toys and lingerie.
If a woman needs medical assistance, a "girlfriend" takes her. This woman is usually the pimp's girlfriend or a "retired" prostitute in good standing.
If LE show up, the men are always the women's boyfriends or "cousins". The women have lost or misplaced their IDs.
Women are procured by other women and lured into meeting the pimp. The woman will be lavished with attention for a short amount of time until she is introduced to the lifestyle. It is very much a form of grooming. Once a trick has been turned, the woman will be shamed into silence and told that she could be arrested or that her family wouldn't want her back. She will be reminded just how much money (manicures, pedicures, hair styling and wigs, clothing, perfume, etc) has been spent on her and that she needs to "pay" her way.
The vast majority of young women involved in this style of prostitution are required to turn 10-20 tricks per day
That's what I know. If anyone has a specific question, I'd be more than happy to try and answer.