Let tags have a score of 0, interesting tags +10, ignored tags -10, by default. Just sum up the score and let the sign determine whether the question is interesting (>= +10), ignored (<= -10 ) or not marked special. But let the score be changeable, so that e.g. [retag-request -20] will make a [bug +10] tagged question still uninteresting.
As an addition, mark tags that have not been manually assigned scores to, to easily identify them. Bonus points for making the highlighting strength of interesting tags depend on the score, kind of like Alconja's great greasemonkey script.
edit Concerning wildcards, please vote on the two @Grace comments to indicate your desired behaviour, or suggest another solution