Furey is a crook. No question about that. Digging up Farmer Burns' instructional and trying to hawk it for an arm and a leg while it was available free online is a prime example.
As for Jake Shannon -
While he is helping boost the popularity of catch wrestling, and has some excellent instructionals on his website, I feel he did more damage to the credibility of CACC with his bashing of Tony C.
Up until guys like Tony C and Furey started pushing catch wrestling, it was generally unknown to the masses (though still is, but is growing), and these guys, including Shannon, were looking to tap into a market where there was a possibility for money to be made. Just as the Gracies had done with their JJ in the early UFC events. The only difference is that Gracie Jiu-Jitsu was proven in modern (at the time) MMA competition, while catch wrestling never had a 'representative' in MMA who was competing for the sole purpose of demonstrating the effectiveness of the art.
Enter Jake Shannon, who thought up the brilliant idea of dragging Tony C's name through the mud to help push his own "Scientific Wrestling" products. Had Jake simply started pushing his own products without the smear campaign, he probably would have done just as well, and would not have created all the controversy and questions about the credibility of CACC. Here now is a an example of the pot calling the kettle black. Shannon has, on a few occasions, put down Tony C's Certification Program, which I'm told, takes a few years to complete, and he's only certified a handful of wrestlers to date. Meanwhile Jake has his own Cert., which consists of a few weeks of training and about $1000 to become a "Certified Catch Wrestler". Sounds great, until one of these "Catch Wrestlers" gets owned by a BJJ blue belt, leading to the belief that catch is no good.
In my opinion, Furey is a douchebag with some legit skill, Jake Shannon is a snake, and Tony C, who's been on the recieving end of bad publicity, is a very legit grappler and a decent instructor, although he is an asshole and is full of himself.