my personal experience has always just been knowing someone who knows someone, but some of the blue collar bars i frequent or have frequented, you can pretty much figure out who is one by just hanging around, just get to know people in there, shoot pool, talk sports, its pretty easy to get in the loop if you got people person skills. me, i've always worked construction or warehouse jobs, and almost everyone gambles, so someone knows someone.
so just hang out at bars where construction workers,warehouse, basically blue collar shit job workers go and you should find one.
rich people play the stock market, poor people gamble, that means scratch-offs, bingo,lotto, horses, sports, anything for a quick buck to give us our daily high.