When you hear a great producer work with a terrible artist, do you think of them as musical individuals or does the artist bring the producer down to to his or her level?
You do realize this is impossible and does not exist, don't you?
a) If you are a producer and you work with someone and they (still) sound terrible, you are not a 'great producer'.
b) If you are great and worked with someone and a result was TERRIBLE, we would never hear it. We'd only hear the good stuff.
c) If you worked with someone and nothing...worked...you'd STOP WORKING WITH THEM and we would never know you ever did. Unless of course they blew later and then youd mention that you worked with them 'early' but the label never put it out. Lol
The only case this makes sense- is when you hear a 'dope beat' rhymed/sang over by someone you don't like. That's your opinion and you don't know how how much worse that artist might sound over a weaker track. I think they are a lot of rappers who benefit from music better than their vocals. Hell some are legends. And there are some rappers that make whatever they rhyme over sound better than it really is. so....
From an abstract sense, the music usually comes first. I don't know how many producers truly work off an freestyle acapella verse before they start creating.
And if that verse is wack, they are going to be inspired to make a wack track too.
If anything, I'd say you might over-produce trying to save the vocals- adding all kinds of bells and whistles to help.
bah