The credibility rating is a compilation of the "best qualities" or characteristics of a jyte user. Adjectives are always descriptive, whereas nouns are often not. A characteristic can be a noun, but such nouns are usually variants of better adjectives.
For example, funny, amusing, comical, humorous, hilarious, clever, ironic, witty, whimsical, silly and sarcastic all describe a person directly. Meanwhile, laughter, comedy, humor, wit, irony and sarcasm are qualities that a person may possess.
Discussion (1)
But you can be knowledgeable in a noun, say OpenID. Then that's a great cred to have.
I think cred should match well with tags. So, it depends what you think works well for both.