@ginghamstarfish
I would agree with filming them, or even just pretending to. I remember having this kind of thing when I was a teenager, no phone with camera then, so I took to whipping out a notepad and pen and very obviously writing down the car reg number, or at least pretending to. Most of them sped off. Yes, we should not have to do it, but there isn't much else we can do. Kerbcrawling and suchlike should be arrestable offences, but the police clearly don't care.
I've seen it from both sides, as I said earlier I grew up in a notorious vice area, we used to feature in The News of the World occasionally. Then I grew up, got a job as a civilian with police and eventually moved to vice squad. Honestly they did try but several things happen:
Streets flooded with police doing a crackdown - something happens elsewhere in the city and there is a newspaper campaign about the police hassling prostitutes and clients when someone is murdered/raped/ assaulted in nearby area. Everyone up in arms, councillors and MPs involved. Crackdown ends.
Or crackdown is very successful, prostitutes move to adjacent areas in another division, residents up in arms, councillors and MPs involved crackdown ends.
Or rape happens nearby, police blamed as men who would have paid a prostitute have a raped a young mother/schoolgirl/helpless old granny, newspapers outraged, councillors and MPs involved, crackdown ends.
I have actually seen all those scenarios play out. I've also seen a new senior officer arrive who decides to solve the problem, good for him. The above scenarios play out, he decided to focus on something else.