When is fuel too cheap?

We generally check prices for diesel fuel from one state to another. With a 270 gallon fuel tank - we have quite a travel range, so we can often avoid filling up in states that have a high fuel tax, or higher fuel rates in general.

I was checking rates as we were heading across Mississippi to Louisiana - I could see that the Pilot in Louisiana had higher rates (2.33/gal versus 2.11/gal at "car" fueling stations in Mississippi), but I wasn't finding a Pilot in Mississippi. So... using AllStays, I just looked for truck stops - and found one in Vicksburg - just 5 miles from the border. I looked on GasBuddy, and it didn't have a rate listed for diesel... but it was a truck stop (Kangaroo Express) -- surely they would have diesel?

We got off - the station is just north of I-20 at exit 5A. There is an entrance north of the station for trucks to use, and they have 4 diesel pumps behind the building and the price posted was $1.86. Yes, $1.86. That's almost 50 cents per gallon cheaper than the Pilot that is just a few miles into Louisiana.

Miss Doozie was thirsty - 134 gallons worth...

The only downside was that they didn't have "pay at the pump", but that wasn't too much of a hassle. There were other truckers filling up there; I asked one of them why it was so cheap, and he said, "I don't know, and I'm not askin'!"

We drove about 80 more miles and Miss Doozie seemed to run fine on this fuel - is there a point where the fuel is so cheap that you figure there is something wrong with it?