In all honesty, bad lyrics are bad lyrics. A good vocalist can make the 'sounds' work, but when I hear the words it doesn't make the song anymore interesting regardless of how well the song sounds. I will always like the vocals just for the sake of the vocals, nothing else. That's not making it as good as it could be.
The only thing that can save cliche lyrics is good musicianship, emotion, and vocal talent. But a cliche lyric is a cliche lyric, there's no hiding that. It's going to affect the song adversely, and of course it depends on the band how much it might.
I think with metal and hard rock bands we listen to them with lower expectations in regards to lyrics. I don't know if that means lyrics don't matter as much. We just tell ourselves that metal bands don't write good lyrics but we are going to focus on other parts of their songs.
But if I throw on some folk or prog you better believe my expectations are going to rise back up to a higher standard.