Quality score is treated as a mysterious factor by AdWords advertisers as Google never reveals score of individual keywords. Recently, Barry Schwartz from SERoundtable has discovered a new column in his campaign called Quality Score for each keyword. The score is either Great or Poor. You score Poor most likely because your keyword is inactive and you have to raise the minimum bid.
The Quality Score column displays your keyword's Quality Score to help you monitor your keyword relevance. This is a customizable column that is disabled by default for new accounts. It can be enabled at any time.