Haven't tried this in Blackpool specifically, but after having a couple of bad experiences I started applying a couple of rules and although I've only seen a couple of Roms using this theory, both were actually good and I'd see both again.
- Permanent location or limited repeat touring locations - if they can make money without moving to a completely new area on a regular basis, they must be getting repeat customers. That doesn't happen if you give the stereotypical Rom style service, so they must be doing something right
- Pictures: Regularly updated, not professionally done, and looking like they're enjoying themselves whilst taking them. Lets face it, most of the shitty Roms have limited pictures that are all done in a single session and which never change. Even in a photo, you can see a difference between a posed smile and a genuine one, so if they're enjoying that part of the job the chances are they enjoy the rest of the job.
Obviously there are no guarantees the theory will work universally and with only a couple of girls I've tried it with it's not exactly a representative sample, but I was right about the two I tried and I've seen the occasional positive review on here of others the rules would apply to.