I generally try to avoid sampling other producers' material, especially
melodic material, at all cost. My only exception would be the isolated break
beats on various tracks, but even then I'd try to use them in a different way.
Anyone with good exposure to current music and a critical eye will discount a
track that bites a beat or sample extensively. Yet ironically, often the
best-selling singles have big chunks of others' work. Recognize the beat on
"Killing Me Softly"?
Your question highlights strong difference between the "if it sounds good, who
cares where it came from" perspective and the "I must create something new"
perspective. I don't think any definitive answer can be given as to what
other people will think on the street about biting a sample - the difference
between rip-off and recontextualization is too vague and subjective for any
given track. I think the more important thing one should focus on is
employing whichever creative viewpoint makes one feel the most comfortable. I
understand both, even though I am heavily biased towards the latter
(originality) in most cases.
Jay B