I think your efforts should be applauded buddy and unfortunately is probably the only sure way to go about things. I’ve been doing a similar job in my home town and leaving reviews. It gets a bit tiresome doing B&S though as I’d just like the girl to be the one in the photos.... hence visiting the likes of Zelda/Victoria when in London..... still nonetheless I’ll keep probing until I find my ideal hidden gem.
Cheers, good work reviewing in your hometown. If you team up with some locals, it will be easier. If they report a good find, then everyone can flock there. If they report an avoid, you can search elsewhere. We do that in East England and it works well. I'm thinking of something similar for London.
Lately when I visit London I visit at least one B&S place to see what's on offer. And then I have standard AW hotlists to check out as a backup.
I have several reviews to write from my searches when I have a bit more time.