I was wondering this and is a bit difficult to test since they only update once a day it seems. Do you actually lose the points that count toward the badge for specific tags? For exmaple, if one were to have 100 upvotes in the c# tag but have a few downvotes, would that mean they didn't get the badge (until upvotes - downvotes in that tag hit 100?)
What is a tag score?
A tag score is basically the combined total of all the upvotes (+1) and downvotes (-1) you've accumulated on answers under that specific tag (votes on questions do not count). As well, posts which are in community wiki status or that have been deleted do not count towards your tag score. Tag scores are only recalculated once daily, at 03:00 UTC.