While I don't put much stock in boycotts, I can understand why these folks were excoriated. There is no possible brief for apartheid. Now, in 2011, we are learning that entertainers weren't so shy about performing for a monster on the other side of the African continent:
What a relief that Nelly Furtado has decided to give away the $1-million fee she received for performing for the loathsome Gadhafi clan. Now that blood is running in the streets of Tripoli, other entertainers are rushing to follow her example. Mariah Carey says she feels “horrible and embarrassed” by her New Year’s Eve performance for the Gadhafis three years ago, and although she has refused to donate her rumoured $1-million fee to charity, she’s promising to give away the proceeds from a new single to human rights. “I was naive and unaware of who I was booked to perform for,” she explained.
Entertainers are one thing. Others who should know better took Gadhafi's money, too. There's a lot more at the link and you should read it all.