Every paint job has flaws, even new ones. With an older paint job you can use the truck and not be concerned about every rock chip or sticky fingered kid. I've done enough shiny new paint, it's tiring and doesn't make it any more fun.
Is it bubbling a lot? I'm curious why you're so concerned about rust underneath and what other flaws it has?
If you clean it up nicely to get the staining off and a good shine on it you might be amazed how awesome it will look.
