Singing is an interesting thing. There's people who are great singers that don't have good sounding voices (think Dylan, or even Bruce) and people who have great voices but aren't technically good singers (think Mariah Carey--her phrasing is abysmal). Now, there are a few singers that have good voices *and* are good technical singers--and these are the people that there is general agreement on. You make a list of these people as "great singers" and you generally don't get much argument. Marvin Gaye, Elvis, Paul McCartney, David Ruffin of the Temptations, Kate Bush, (to get out of rock a bit) Sinatra. That's a few of them. Anyone that tries to tell you that Marvin Gaye couldn't sing doesn't know anything about singing.