Great idea - I'm in! The first vocalist on my list is Brian Johnson of AC/DC. I think I'm a bit like a former heavy smoker who developed an intense aversion to cigarettes upon quitting. I used to listen to screaching high-pitched heavy metal vocalists almost exclusively, and now I find it extremely grating. Brian is the most prominent example for me because my son is now listening to a lot of AC/DC, but you could substitute Geddy Lee (in the early years) or any number of others from the genre. My second choice is Axyl Rose. In many ways he could be included in the first category, but I'm listing him separately because he is such an ass. Also, his voice has a certain muppety quality that I find particularly unpleasant. My third choice reminds me that this list is not in order of priority, because Johnny Rotten might be my all-time least favorite. His vocal style of spitting out the lyrics with little or no regard to melody and absolutely no dynamics spawned countless imitators and I detest all of them. I get the social dynamic of the band, and there is undeniable power and energy in the best punk music, but that vocal styling ruins it all for me. Bringing it closer to home, and switching genders for a moment, I'm going to name Carole Pope of Rough Trade as my fourth example of god-awful singers. Her musical footprint is much smaller, but she did invade my otherwise idyllic universtiy years by "smudging the air with her sound" as Leonard Cohen would say. My final choice is a bit different - Richard Thompson is an excellent guitar player and songwriter, and I would like to be a bigger fan, but there is a quality in his voice that puts me off. I can't put my finger on exactly what it is, but something in the timbre of his voice reacts badly with something in my ear.