Just curious, is there a website where providers review clients???  Not necessarily performance, but a heads up if other providers should avoid this or that client like the plague....a kind of blacklist....

No one has the exact number but between national and local blacklists there are literally thousands of places clients get listed for offenses.

Not all lists are of bad guys. A few list nice guys to let women know of good clients.

Do providers use NBL?  Doesn't seem reliable since they don't screen who submitted blacklist. Search is by email or phone which client can easily change.

are themselves dangerous, and I stay far away from them.

Hobbyists get outed with their personal information for simple infractions. I have seen guys outed for canceling appointments, newbies asking the wrong questions get outed and the hookers who frequent that site can do it anonymously. Some of the hookers out hobbyists as reprisals and punishment for bad reviews and even postings on TER.
Their outing of personal information is able to be found via google search.

If you need a legitimate site dangerzone411 has been around for a long time and has a reputation for being fair to hobbyists while maintaining the purpose of keeping providers safe.

Since I'm not a provider I don't use these sites, but I have seen people outed on them and yes occasionally a provider will retaliate for getting unfavorable reviews and list clients there.

Funny, the provider who used to be #1 in my area is no longer listed here on TER.

I think it is important that these sites exist in order to protect the providers from the creeps, time wasters, thieves, rapists, etc.

providerbuzz.com