The euphemism treadmill is a mechanism for regularly and arbitrarily destroying a random percentage of non-leftists using the primary weapon of leftists, which is language. Every few months or years, the left decides that a label has accrued too much negativity (or accuracy) and must be summarily retired. The delta between when this decision is made and when conservatives find out about it is the peripd of time during which leftists can snag the most conservative scalps. This delta is significantly widened if the rules are murky and incoherent, and so leftists endeavor to make them so.