Davey Graham was great in the 1960s - but, as you say, drugs caught up with him and his playing deteriorated.
He was still playing (only occasionally) 10 years or so back here in England. A friend of mine went to see him in concert and said he was absolutely dreadful. A sad way to end a career built initially on such a talent.
On a brighter note, he also played the oud - this fits with your "world music" comment above. Though, to be fair, it was a Guild player, Richie Havens (of Woodstock film fame), who did at least as much to kick WM off.
