I have to admit, for the first time ever I literally unplugged another car at a level 2 charger. I rolled into the single charger with 0 miles on the dial and the car was about to die. I unplugged and got about 15 miles on the charge so I could get to the nearest Supercharger. I did kindly plug back in the other car when I was finished, and even restarted the Chargepoint charger on my account. So, it was an emergency, and I was courteous about it...
That said, for all that read this - it is a dick move when the Supercharger has plenty of room and you pull in right next to someone else charging. That happened to me the other day... and I just shot the guy a look and moved on. Didn't really say anything, but regretted not.