Usually a member of the indie or punk music community that ends up performing vocals for a band due lack of any real musical skills. This can also be with underground hip-hop. A person which may be good looking but lacks any musical talent. A person who can be abrasive and does vocals out of needing to be in the spotlight. This type of music scene is the only that permits shitty singing as a trademark and isn't as strict on vocal stylings.
I know the singer of that band! He used to play guitar for us and was fucking horrible at it. Yeah, he is a vox by default musician now.