Laird Wilcox did a study on this stuff in the early 90’s. The title was ‘The Hoaxer Report’ and it addressed such hoaxes on both the left and the right. The vast majority were on the left. His study indicated that ‘more than half of the incidents reported were hoaxes perpetrated by the person reporting them.
I just tried to find that Laird Wilcox piece you were referring to....did you mean “The Hoaxer Project Report”, which Wilcox apparently self-published in 1991?
I couldn’t find any copies of it for sale, but the few books that I did find that quote it refer to it as an examination of ostensible skinhead and anti-semetic vandalisms, not as perpetrated by leftists.
That won’t help me explain to these guys that 99% of these “vandalisms” are really perpetrated by the Leftist Democrats to get sympathy and news!