Saturn ion fuel injectors problem

My moron friend owns a Saturn ion, not sure what specific model.

It was running really bad (don't have much more than that), so he took it to a Saturn service center or whatnot. They told him he got "bad gas" and that they need to replace the #3 injector. His car ran fine for about 5 miles to our house and then the next day started messing up again.

My questions are: is there such a thing as bad gas? (I'm almost sure there isn't, one that can clog a fuel injector anyway)

What could be causing this problem? A bunch of things, right? What about the fuel injector problem? If it is the fuel injector what could be causing it?

Any help would be good. I know that it is almost impossible to tell with the information given.

I have a hard time excepting dirty gas as causing problems in a newer car. I would expect the fuel filter to take care of any damage causing particles coming through the line.

Beware of some saturn dealers. A lady friend of mine was in Kennasaw Ga. with her saturn (36000 miles) with a dead battery. The dealer there told her because she went over the 3000 mile oil change interval, that she had to have an engine rebuild. She called me and I told her to have the battery charged then drive it straight to the dealer in chatt. She did,they changed the alt. and she traded it in 4yrs. later with >160,000 miles. The motor still ran fine.