It's worked well for me in Brighton, Gatwick, Tunbridge Wells, Maidstone and Ashford.
As others have said, mainly older white men, often they just want a quick rub and tug or a BJ. I've had some really nice guys through there.
I have heard from friends though who price higher than me that it's been pointless as the guys aren't looking to pay much more than ?70/half hour max.