Do you believe this "garbage in , garbage out" saying is true?

I was watching some videos of George Carlin one of my favorites.

It would be better if you watch the video to get a full understanding at what he is basically getting at. There is some cussing in there but nothing too serious but just so you know…..

http://www.youtube.com/watch?v=xIraCchPDhk

My question is how true do you think this is?

Surely of course I know not everyone is like this…..But in the end it makes sense does it not?