Someone parking so close to another person's car that they could not open their driver's side door wide enough to slip a can of soda through the gap into the car deserves to have something bad happen to his or her car. I've never done anything like that in my life and cannot imagine parking so that I prevent someone else from getting into his or her car - it is unbelievably rude and thougthless behavior.
Spyder, I've never keyed, kicked or otherwise touched anyone else's car just for double parking, and I walk by a new 911 at least once a week whose douchebag owner takes up two spaces in a very crowded parking garage. How is it that you are not capable of understanding that taking up two parking spaces (which may or may not effect anyone else in any way at all depending on the parking lot) is an entirely different situation than parking someone in so closely that becomes difficult for either driver to exit the parking spot without the cars scraping? Totally different situations. Analogy: saying "If I saw a guy wearing poofy plus-fours and a beret out on a course, I'd punch him" is not the same as saying "A drunken jerk called my wife a wh*re and gestured as he if was going to fondle her chest, so I punched him." One can joke about the one situation (which clearly would not be justified and was made to be humorous) but actually committing the act in the second situation would be justified. A little more thinking and a little less mischaracterizing and jumping to conclusions will benefit you Spyder.