I've actually recorded a few EPs for some hardcore punk, cookie monster vocal type bands. Can't stand the vocals. I had one band where the singer's vocal chords were bleeding and he wanted to sing, because he didn't want to stuff me around!! I told him to come back when the doctor said he was ok.
The funny thing is that when I did the first band, a friend of mine got really angry and told me I shouldn't do it, as I wasn't into heavy music. I did the other recordings, all on the strength of the first recording. A guy in the last band I did, a few years ago, asked if it was true that I wasn't into hardcore? He thought I must have been some sort of hardcore fanatic, as nobody else recorded it as well as me!! Fortunately I haven't been asked to do any for a while now.....
I had another singer ask me to make his voice sound like broken glass, so that nobody would be able to stand listening to it.