I know for a fact my favorite MC has used a ghostwriter or "collaborated" with others on curtain hooks for songs. That doesn't bother me as a oppose to half or all an albums worth of songs.
The way I see it, if you're a famous MC unsigned rappers are constantly giving you demo tapes and mix tapes asking you to help them get signed. If somebody gives you a mixtape and there's a banging song on there that totally fits your image I could understand why you'd work out a deal with the unsigned rapper to re-record the song under your name and pay him a royalty as opposed to releasing the song under his name. Because its just more competition if he releases the song under his name. If you re-record the song for yourself its a win-win for the famous rapper and the unsigned MC.
