I agree with the sample anything- anywhere philosophy, but c'mon guys -- mp3's sound horrible. You can get a better sounding sample from a VCR. No joke. Vcr's used to be used for studio backup, like DATs were.
Mp3's sound like washing machines in the background.
The files don't sound 'warm'.
No amount of filtering, eq, compression,tape overdrive, timestretch, whatever is going to put back in what was never there in the first place.
Mp3's are so compressed that there's no 'space' in them.
So instead of having grooves in a record made by an acoustic transducer, you have an audio file of 1's and 0's, and alot is lost.
All the sounds are the same volume, it loses alot of the dynamic, human feel.
If you have to sample digital, try .flac