I love ole Alice, his voice is one of a kind, bum notes or not. Mark Farner was in contrast a very good singer, he had a tone that always reminded me of David Byron of Uriah Heep - WILL YOU STOP DROOLIN' MARK! - who in his heyday was also a very good singer (if a bit on the operatic side) - before the drinks caught up with him.
Pity that Rough Diamond went nowhere after that very promising debut. Byron and Clempson were an unlikely but gifted combination.