Most of us know about the importance of maintaining a separate number or app for POT communication. But I'd like to illustrate a case that really highlights the importance.
I connected with a POT (for reasons I won't get into, it didn't work out) and only had her first name and phone number. Turned out it was her real number and when I plugged it into Venmo I got her last name.  
Even though it was a very common name, a Google search using her location found her current and former addresses as well as names of family members (some of these shady websites will look for court and criminal cases if you pay).
Searching further, I discovered that she had been a nurse, but that her license had been suspended.
She had at least three appearances before the licensing board, and the documents I found showed she had entered into consent agreements that could conceivably allow her to get her license back but not a lot of details. (She is not a nurse now, from what she said.)
However, looking at the state licensing website, I found what had happened: She had stolen drugs from the hospital she worked at for her personal use and had been addicted to heroin and other substances.
This wasn't a complete surprise. She had told me she had had a 'substance abuse' issue but had been clean for some time.  
She still came across as a responsible person who seemed to be working hard to improve her lot. She might have made a good SB.. that's another story. The lesson here is that a little sliver of info can be used to dig up a lot of info on anyone.

Years ago I connected with a woman with her real phone number. A background search revealed that she was on parole for sex with underage students where he had been a teacher's aide. Received big media coverage in her area. I wasn't about to touch that with a 10 foot pole.

Related, I just recently connected with a very attractive woman on SA who said she has been "clean" for 15 months. I didn't ask any further questions. Clean can suggest any number of issues; while I wish her well, I don't need that kind of potential drama if there is a relapse.

I approach vetting a new potential SB as if she was applying for a job. I don't have the full set of tools that a corporate HR team has, but I use what I can to do what I call a "negative" vetting. Negative vetting means ensuring she is not a scammer, does not live outside my targeted geographic area, is not physically as described in her profile, is not a drug addict or alcoholic, is not being managed by a pimp, and is not a catfish.  

 
Doing this is a blend of science meets Spidey Senses.  I use a mix of web search tools (some free, some paid), plus my "red flag" experience to verify as much as possible before a M&G. If possible, I will also use any intel I glean at the M&G to do additional searches.  

 
In many cases, no news is good news, meaning if I don't find hooker ads, criminal activity linked by her "real name," phone, email or address (if I have any of these), I take that as a net plus. Better to find nothing, than a bunch of negative. Better still if I can verify her real info.  

 
Since I do not have an S/O, job, or "unaware" family/friends that could make me a blackmail target, I also try to make it easy on her to vette me - once I am comfortable that she is who she claims to be. I offer a copy of my ID, my LinkedIn profile, and when the time arises, a full copy of my test results showing my real name. Sadly, far too many of my POT's never use this info to vette me.  

 
As for the POT vetted by the Mouche, he did a good job of protecting himself and probably avoided a lot of serious problems.  I wish that POT well, hoping she is able to stay sober and gets back on her chosen career path quickly. But my experience in the past with SB's who abuse substances or have detrimental psychological issues (ex: Bi-polar) makes it clear that I should never be part of the recovery or support process.  

 
Life is good

 
The Cat

This is all great advice, but sometimes, you just don't know.  One of the sweetest, sexiest, long term SB arrangements I ever had was with a young beauty who was secretly drinking herself to death.  I had zero clue.  When she died at the age of 26, I attended her memorial service and discovered that she had soooo many friends who were equally in the dark.  All of whom would have bent over backwards to help her, if they'd only known how much trouble she was in.  Sometimes you just don't know.