When I returned my (expensive) rental to BNA with a full tank of gas, I did what I always do. I snapped a photo fo the dashboard showing a full tank as well as the car exterior at several angles. I asked the return-attendant if everything was okay and he said yes and he's emailing me the receipt. I made the mistake of taking his word for it and leaving for the terminal.

That night back in my hometown I see they charged me about $60 for fuel! I opened a case with them via their website and all I got back was a forum email basically saying they are looking into it. I responded with the photo of the dashboard and the photo's metadata showing the time and location of it. No response for about two weeks so I called them and spoke with an agent with my case number. They finally refunded the erroneous charge.

Yeah I got the charge reversed, but that they actually tried this trick is a testament to the culture that is permeating the rental industry lately. It's a reminder to be diligent. Save fuel receipts. Take photos. And do what I didn't and check the receipt before you leave the rental car lot.