It is of interest to note that Jimi Hendrix did not want to sing. He knew his voice was not on par with a 'singer's' voice but he was encouraged to do so because he had a syncopated style of 'singing' the words that matched his eclectic sound. He probably had trouble singing and playing as well....
http://www.rollingstone.com/tv/news/fiv … x-20131106
"While his vocals obviously aren't as virtuosic as his guitar playing, they're more than capable – but Hendrix was intensely self-conscious about them. "We had a constant row in the studio," Chandler remembers, about "where his voice should be in the mix. He always wanted to have his voice buried and I always wanted to bring it forward. He was saying, 'I've got a terrible voice, I've got a terrible voice.' I'd say, 'You may have a terrible voice, but you've got great rhythm in your voice.'