Having starting my punting career on the streets I can understand why people go hunting there but personally I would never go back to it.
As Steve says, what you see is what you get.
However, what you tend not to see because you are looking solely for likely street walking candidates are the CCTV cameras, ANPR cameras, potential police operations hiding in the background and pimps hiding around the corner.
These days you don't have to pay much more to get a 15 minute quickie off AW as you do to get less time with a strung out street prossie with all the added dangers. No contest really.