Why are you assuming the client didn't pay? You know absolutely nothing except that the designer ripped down the website and replaced it with a nastygram. Given that information, I'm certainly not quick to rule out the possibility that designer may be the asshole here.

Or in your mechanic example, maybe that mechanic quoted me $500, and then I show up and he asks for $1500 instead. I don't want to pay $1000 extra, so he threatens to spray paint my car with "balloot is a cheapskate" and park it out front of his shop.

How do you have any idea this isn't what onemine.com isn't doing to the grocery store?