During the Buffalo Rally near Port Elizabeth a few years ago, a gang of about 20 big, mean-looking, unwashed bikers stopped at a small town on their way to the Rally. They all but invaded a little convenience store there, buying crates of Coke, a few loaves of bread, a pile of cold meats and dozens of packets of crisps.
The shop assistant was terrified, and expected at any moment to have a shotgun shoved in his face.
Just then a group of well-built, well-dressed, clean-cut young men who looked like wealthy farmers' sons walked in. The assistant relaxed, sure that these respectable sons of the soil would protect him from the bikers. Sure enough, the bikers paid for their goods without a murmur and walked out.
The assistant turned to one of the young men and said: "Shoo, am I glad they're gone!"
To which the respectable customers all responded, "Ya, so are we!" and pulled out their guns. They cleaned out the till, and disappeared with the money the bikers had just spent.
As in most urban legends, the moral of this story is obvious: don't make assumptions about people based on their appearance. In the land of urban legends, the consequences are dire.