I have several requirements when I write a lyric:
- I feel that lyrics should tell some sort of story - listeners/readers must come away knowing something they previously didn't. Also, it must be something that both myself as a lyricist, and other people as an audience, would care about. Do people want to hear about my smelly socks? Probably not.
I do my best to avoid all cliches. Nothing kills a good lyric for me more than cliches.
I ask myself - "have i told this story before?" The idea for the lyric must be new, or must be from a new perspective, or bring something fresh to the proverbial table.
As several people have mentioned in this thread already, the lyrics must have some discernible rhythm that myself or other musician could put to a melody.
Lastly, all the words in the lyric must contribute to the overall lyric. Rhyming strictly for the sake of rhyming is forbidden.
Hope that answers the question for you, Lazz.