According to the people at the store the PS pumps are tested with ATF so that's why the one I got had some in it. I have no way of knowing the truth of that statement unfortunately.
My 1973 Chrysler service manual says in the maintenance section to fill the PS pump with the power steering fluid and in bold print "Do not use automatic transmission fluid". Personally I've never used ATF in the PS pump of any car I've owned.
Autozone used to sell really lousy parts, especially their electrical parts (although I once bought a turn signal switch for my Firebird there that was a re-boxed Delco switch, and it has lasted me a long time), but now I'd say the majority of their parts are on par with Oreillys, Carquest, etc. Other than possibly NAPA - which we don't have here anyway - there's really no other places to buy parts that MIGHT be any better other than to order them from somewhere like Rock Auto and pay thru the ear for shipping (I always hate it that their parts always come from multiple warehouses and they charge you separately for shipping for each one). I figure with almost every car part being built or rebuilt in developing countries like Mexico or China nowadays any new part you buy is going to be about the same in terms of quality, and you better make sure you get a warranty with it.