If I were to start a PUG, I'd definitely ask for achievement link (which means they're familiar with fights) and armory them to make sure they are epic'd out. Why? Because I want the smoothest run possible and the more geared people are the more room for error we have.
Yes, it's that simple. Nothing personal, just common sense to choose the best.
Why are you worrying about not getting into Naxx when you aren't fully epic'd out yet? Heroics, emblems and reputation gear alone will give you all the epics you need to look "presentable" for people requiring gear checks.