I am sure Druff's comments made a while ago, where more about B&M casinos, probably here in Vegas. But you would have to ask him.
I don't think a B&M casino or chain of casinos like let's just say MGM, has people who's sole job it is to scour social media and gambling forums. But there are people that work for them that may visit this or other forums, maybe even on their own time. I have a friend that works for that particular chain that visits this forum occasionally. I think mostly from home, but he may very well have visited on his break from an IP address that would have been a casino. I have no idea.
Now the databases companies, I do believe have people, maybe only one or two that monitors online sources for any information that can be helpful to them. That is their business.
What I can tell you is that when I was doxxed, (which the primary doxxing occurred on another site not here, but some of the information was repeated here), there was a piece of information that was incorrect, that turned up in a database entry. That is a "marker" or proof of where it came from.