Sure the best quality sample is preferable. Who wouldn't agree?
I've worked for quite a long time in professional recording studios, sometimes (shock horror") we lifted samples from vinyl, and directly from a TV via cheap microphone. We kicked in amplifiers, we coughed all over the records. We even got stuff off cassette...
And guess what, a lot of those records were hits. They had a certain characteristic to them... When you realise the overall sound has distortion all over it you get to understand what you can live with and what you can't. And sometimes that weird thing you picked up the vinyl scratch, the tape hiss, the nasty sound the MP3 sound made when trying to compress a Hammond organ is exactly what I'm looking for.
Oh and some of those Fairlight samplers were nasty... yet they added their own uniqueness about them...
It just depends on what you want, if I was recording spoken word or the LSO I would take a totally different approach.
Not everything necessarily has to sound like Dire Straights...