One of the reasons I like virtuoso guitar music is that it doesnt need vocals to screw it up. Some like Steve Vai have ended up making less good CDs because of cak efforts at singing. Second half of 'Fire Garden'? Satch just about pulls it off on 'Flying..'.

For me there are very few decent singers in rock. i find Freddie Mercury's style over the top.
overrated? all those divas that are more interested in vocal acrobatics than sounding tuneful. Mariah Carey, Whitney Houston, Celine Dion etc for me are the Malmsteens of singing. technically perfect but soulless.

great singers are not those than have a 3 octave range and can shatter glass with a top C. great singers are the ones that can have you crying in your beer. Scott Walker, Righteous Brothers, Mamas & the Papas and most of the Soul greats from the 60s and 70s