The only thing I've heard about these no-name stations is that their fuel may be older than the name brand stations.
BTW, around here, premium runs from $1.619 Hess to $1.799 Gulf. There aren't that many cheapie stations in this area, and the ones that do exist are charging within pennies of the name brands.
Hess seems to be buying a lot of Shell and Exxon stations, and they are about the cheapest "name brand". There are a few refineries in Philadelphia, and Buckeye pipeline company is pretty close, so maybe we get pretty fresh fuel. I did have Getty premium freeze in my fuel line once, but that station is now closed.