Well the fake bots will post fake comments and spammy links and stuff too, so it's right in front of you for the most part.

I dunno, I poke around in followers a little bit but it's usually to the tune of "what other developers follow this person? I might want to follow them too". Not that I use twitter much so eh. Maybe that only really works on the smaller accounts I usually look at. S:

I had an Airbnb guest who left our apartment a mess. I left a review that reflected that, and this person harassed my wife and I to get Airbnb to remove the review. Upon looking this person up, I found they had tens of thousands of fake Instagram followers. While not a clear indicator that I'd be dealing with a troubled individual, it was interesting to see the correlation.

When I'm buying or selling music equipment on Craigslist, if the value of the item is in the hundreds or thousands, I'll definitely do some social media research before meeting up in person, and I don't think it's ever been a make-or-break kind of thing, but it helps paint a picture of who I'll be dealing with.