In the late 50s and early 60s there were some cross over artists sneaking into the top 40 charts; Bo Diddley, Huey Smith, Bobby Blue Bland, etc. These were the ones that took me away and felt good. I didn’t know why, they just did.
For me the shock was not just what B.B. King did for and to me on that summer camp trip, but getting home from that trip to discover the freshly-released “The Thrill is Gone” had crossed over into being a huge hit.