What is it about mimes that so upsets Lord Vetinari? He has banned both miming and the performance of street theatre within the walls of Ankh-Morpork, but the emphasis in the books and most attendant material is on the banning of mime. Anyone found wearing miming clothes in the city will be strung up over a scorpion pit opposite a sign which reads "learn the words."
The reason for this is never given, and indeed, it is suggested that this may be seen as a little pecadillo or possibly an amusing character trait.
One suspects, however, that the mimes do not share this assesment.
So what exactly does the Patrician have against mimes? One theory I have heard is that they misuse that precious commodity, silence. By using silence as a form of entertainment, they trivialize one of Lord Vetinari's many tools of the trade. His Lordship's ability to remain silent and use that silence to get people to talk is often commented upon.
I suspect, however, that the cause is a bit more devious than that. I propose a different explanation*: namely, that Lord Vetinari felt it necessary to have some apparently random and cruel law attributed to himself to keep people on their toes.
Banning mime is a wise choice, as it is found annoying by most people, serves no practical purpose, and the punishment of infractors will have little effect on the average person. Indeed, many people actively dislike mimes, so prohibiting the practise of mime may actually have raised the overall civic morale!
There are, of course, those who will argue that the morale of those suspended over the scorpion pit is far from raised by this statue. To them, all I can say is: one cannot make an omlette without breaking a few eggs. (and, of course, the obvious: it's just a book!)
* Aside from the dull practical one, that Mr. Pratchett was just looking for something weird and cruel to attribute to Lord Vetinari.