Here’s another quote to add - by Jennifer Granick (director of Stanford Law School's Center for Internet and Society):

"Using an open wireless access point isn't the same thing as using a computer illegally," says Granick. "Convictions for this type of thing are possible where it's part of a larger criminal case, but it shouldn't happen in the absence of some other criminal purpose, like stealing credit cards, or knowledge that the network is closed. Wardriving isn't criminal."

It may not be “Criminal Behavior” however it is most assuredly “Deviant Behavior”. Scarfing access, that you would normally have to pay for is unethical. A deviant strays from a principal or standard.