For example, the populist badge is awarded when an
Answer outscored an accepted answer with score of more than 10 by more than 2x
This can obviously fluctuate. For example, if the accepted answer has a score of 11 and a competing answer has a score of 23, then the populist badge is awarded. If the accepted answer is then upvoted, the badge criteria no longer applies (until the popular answer gets two more up votes). Does the badge get lost at this point? Is it lost only if the criteria no longer applies at some later date (e.g. in a reputation recalculation)? Once awarded it's never lost?
The same applies to a other badges, like electorate (voting ratio goes below 25%), taxonomist (tag gets removed from questions), reversal (question vote rises above -5), and even really to any that involve a score (i.e. down votes cause the score to go below the threshold of the badge).