I haven't used found sounds yet in recording.
I intend to though. I've even used them in pieces that I never ended up recording. (like usinbg steel stairs as a percussive instrument).
As for using tapes, I like to tape something, then tape the recording and add anotrher layer and it ends up a horrible screeching sound at the end.
In fact, one of my submissions was a computer error that I had recorded.
I am very interested in found sounds, I especially love it when artists use recorded speech in their shows.