I haven't listened to a pro audiobook since I was thirteen and wearing out the cassette tapes of Starless Night, so I can't speak to the pro audio side of your post, but the things that put me off of a podfic are the things you mentioned: background noise, production issues. Mispronounced words and unclear speech get my goat and will lead me to avoid downloading podfics by that reader in the future, or re-listening to that podfic, but it's rare that I actually stop listening for anything short of incomprehensible background noise. The effort involved in downloading a podfic and putting it on my mp3 player is high enough that once it's on, I'm probably going to listen to it (I'm very irregular about syncing stuff from the internet to my mp3 player).

Style has yet to put me off of a podfic; mostly, when people read passages differently from how they sounded in my head, their interpretation surprises me and I enjoy that. It opens up new ways of looking at the fic, and it feels like a dialogue in my head with the reader.