I'll use stuff that I can't play - like guitars (though I've bought one now and practicing hard) or live drumloops and stuff. I use the sampled loops from time to time if for example I get a computer music Cd and something sounds nice. I don't think there's any shame in using both, but tbh it's so much more fun to make yr own stuff, but it is also fun getting a sample and mangling it into something new.

Sometimes I'll load that into my sampler and use it in a live tune but it's as one of many layers.

Nicking bits of peoples stuff and just loading it into ableton and calling it a live set isn't on though and is just lazy.