I think neil young has a terrible voice, and doesn't deserve to be a star. everybody says that it's because he's such a great songwriter, but I think that there are plenty of songwriters who are just as good as him and better singers too.
well bob dylan has one of the worst voices in the world, but he still makes a hall of fame career out of it. so just because someone has a terrible voice doesn't make them the worst singer in the world.
i went to see a show called Bowser's Rock n Roll Party. For those of you who don't know, Bowser was a guy from either a show or a group called Sha Na Na. Anyway, they had as a special guest Ben E King from the Drifters fame. You know, Under the Boardwalk, Stand By Me, etc. He was a lousy singer. He was better way back when he was new, but he just completely lost his ability to sing. So he gets my vote.
Running a close second would have to be the lead singer of Kansas. Again, he had a really good voice way back when they were new and popular. However, they're still touring, and judging from some live clips and videos i've seen, they really need to stop... or find a new singer.