Depends on what you term reality, Dave. BB King is certainly acknowledged on the single and album track, he appeared on stage with U2 performing the hit, he appeared with U2 on the music video (which incidentally won the MTV Video Music Award for best video from a film in 1989), and more tellingly, he continued to perform the song at his own concerts long after U2 had dropped it from their live performances. On the back of this he went on to record an album with Eric Clapton, and launched a chain of night clubs in the States. I've walked past the one in Orlando. Don't know if any of his contemporaries consider that he has 'sold out', but a hit is a hit, whether it's a collaboration or not.