Well I have certainly without question have gotten bad gasoline. During a snowstorm in January 2002 I got gasoline at a 7-11. My car developed a very noticeable miss or stumble it had not ever had before. I figured out that I had gotten the bottom of the barrel gas from that station. The pump was unusually slow which I noticed when I was using it. Of course, with a possibility of 8-12 inches of snow everyone had filled up their gas tanks. I was very late in doing so. It had just started snowing when I went to that station. It took about 2 tank full of better gas and the car ran like it should run again without the very noticeable stumbling. My lady got gasoline from a WaWa in which her Camry ran poorly. It had a very obvious tick at cruising speed that it never had exhibited before. This car is dead silent when cruising down the road. I went to Exxon and got good gas in it and it stopped. I wouldn't buy gasoline from Wawa, Sheetz or some hoopty Doo station. There is a difference between Exxon, Mobil, Chevron, Valero, BP, and Shell vs the rest. Yes I know some stations get their gasoline from major refineries as well. My step father worked at the BP-Amoco refinery in Yorktown VA. They did have contracts with several unbranded stations in the area. But... It was not the EXACT same gasoline that was made for BP-Amoco stations.