This is a sterotype that, while at one time apparently vibrant and insulting, now seems to be so archaic as to strike most people as a bit of absurdist humor . . . like claiming that Zambians cheat at Monopoly, or that people from Seattle always put water glasses on the left side of their plates.
Nonetheless, it is from this sterotype that we get dime-pinching fictional robber baron Scrooge McDuck (though the existence of Andrew Carnegie probably helped cement Disney's decision to Scotchify their character), as well as the otherwise baffling choice of a name for Scotch tape.
My recent trip to Scotland did not produce any evidence that Scots are cheap. We met Scots of all varieties, but didn't see anyone biting down on nickels in an effort to prove their worth, etc, etc.