If you do a Google search for the telephone numbers of providers who post on BP, occasionally you'll get a link to a site that warns you the provider is actually a trap for law enforcement.  The site seems very sketchy to me--e.g. it has pop-up ads for dating sites.  Still, it's enough to give one pause.

Does anybody know anything concrete about this?

Those sites basically steal provider photo's and info and write fake alarmist reviews in order to get more site traffic/ad revenue. I wouldn't let in inform your decision too much. I'm sure ymmv but I've had a handful of friends end up on there that have absolutely zero affiliation with police. Providers: if it happens to you, you can email them and they will take it down.