A local TV news story about contractors who rip people off uses a quote from a local resident in the ad. The man, satisfied with a local roofer being put in jail, says, "One less scum off the street." That sounds pretty tough, but let's take a look at what it really means, which will also show why it shouldn't be used as a quote to promote the story.
First off, we generally don't refer to an individual as a scum. Scum is usually seen as an amount of something disgusting. Several people could be referred to as scum. One scum-bag, perhaps, but not one scum.
Next, having one less scum OFF the street is a double negative of sorts, really meaning one more scum ON the street. "One less scum on the street" would be more what was meant. Or "one more scum off the street."
Lastly, the street might not be the actual place for rip-off criminals. Generally, I think of the street as where thugs hang out and steal purses. While contractors swindling people isn't exactly a white-collar crime, it's also not the same as a drug dealer who may literally sell drugs on the street. Or those gangs of car burglars. That's the kind of scum we need to remove from the streets.
This might all be because I'm from out of town. I might not understand local colloquialisms. People in Jacksonville might very well call singular individuals scum and disregard double negatives. Like we disregard the apostrophe in St. Johns.