While I actually saw this type of thing happen several times, I will only talk about one particular experience I witnessed while living in Northern California. The Circuit Servant, who typically came around a couple of times a year, was a real pompous, obnoxious type. This was back around 1979. Once when he came around he let it be known in no uncertain terms that mustaches, just like beards, was not acceptable in Jehovahs Congregation!!
I didn't sport a mustache but several of the "brothers" did. And by the end of the week, when the CS had left, sure enough, ALL these "brothers" had shaved off their mustaches. A lot of comments circulated about how different Brother So-And-So looked without his mustache! (Usually, by the tone of their voice, you could tell that what they really were trying to say was, Brother So-And-So looks so much better with his mustache!)
Well, within about 6 to 8 weeks, they pretty much had all grown their mustaches back.
Next time the CS came around, apparently the whole "Mustache-Gate" incident had been pretty much forgotten!