During one of their songs Slipknot has a lyric that they… well, scream: “Your garbage in is garbage out.”
I’m sure they didn’t come up with it, but maybe it’s their shouting of it that has drilled it into my brain.
I like to think of it with a more positive spin. Garbage + garbage will produce garbage. Good stuff + good stuff will produce good stuff.
You may not be instantly inspired with everything you consume, but if it is good quality, it will increase the chances of a positive result.