Never hung out with any of them, but the ones I have met at different functions or dealerships have always seemed nice enough. I take the tact that I am courteous to them, as I would be anyone else I ran into that I didn't know, and they have been courteous in return.
As said, there are 'tougher' people out there, but I don't make it a habit of challenging people to find out if they're one of them.
Are they 'criminals'? I'm sure some of them are. Just the same, the same could be said of anyone who smokes pot, drives more than the speed limit, or fudges their taxes. There are rules (read:laws) and if you break them, you're a criminal. You can argue semantics, or say it's not the same, but it's your interpretation.
"All it takes for evil to triumph is for good men to do nothing." This is true. But so is "Any fool can make a rule, and any fool will mind it." Henry David Thoreau.