As I mentioned, the big hustlers are a small percentage. But the little hustler working his men's group, or local course rota are definitely out there. IT may be you play with a small or regular number of people, and play the same course more often then not. You know everyone and a stranger will stand out and you know people's abilities. I play quite a bit in Florida as well as here in NY and I come across them more in Florida than around here. Maybe because I play with a regular bunch of guys here and don't get matched up with 'outsiders'. But in Florida, I'm teeing up as a single almost all of the time and have more opportunities to meet up with them. A few chunked iron shots after decent drives, a few skulled chips, an offer of a little game "to make it interesting", etc... "No thanks, just out to enjoy myself", but maybe one of the other guys he's been hooked up in our 4 some will bite. I keep my mouth shut about anything other than trying to keep pleasant conversation and make it an enjoyable day for me. Let them learn the lesson. A few take it with a smile and believe it was actually a close match, and others start to catch on later in the round and clam up, finish the round and pay up. Many don't even realize they've been had. It isn't for a LOT of money, but I'd rather keep mine than have to pay someone else's bar tabs.
Maybe it's just a Florida, or East Coast thing. ;) I play probably about 75% of rounds paired up with at least one stranger, and I often go out alone and get paired with 2 or 3 other guys (and I play several different courses - 17 so far this year), and like I said, I've never, in 25 some-odd years of golf, been propositioned by a stranger for a bet. Not one single time. :)