It doesn't seem to be well-documented. Examining the links, there's talk about such practices, rumors, a scientific paper about trying to identify "wu mao" post

It doesn't seem to be well-documented. Examining the links, there's talk about such practices, rumors, a scientific paper about trying to identify "wu mao" posts (which concludes it's difficult to identify them for certain) etc. It is perhaps more accurate to say there is some evidence to indicate this may be happening.