This user http://stackoverflow.com/users/165309/lalit-dhake has asked 25 questions and accepted no answers,
clearly they have a 0% accept and few medals. However simply from the badge it is not possible to know if they are a bad users or a new user (you have to visit their page to know the number of questions they have asked)
I suggest the accepted answer bit of the tag should read 0/25 which clearly shows the lack of the individual. For good users this may get unwieldy (eg 345/350) so perhaps after a certain threshold the badge should revert to percentages.
EDIT: I had not noticed the mouse-over behaviour, perhaps some hint that exists for discoverability... or am I just SO fail?