Joe Boyd said this quote
“ I never knew cocaine to improve anything. When the white lines came out, it was time to call it a night: the music could only get worse. If I joined in, the next day's playback would provide clear evidence of the deterioration of both the performances and of my critical ability to judge them. I suspect that the surge in cocaine's popularity explains - at least in part - why so many great sixties artists made such bad records in the following decade. ”