I don't know that he has "fleeced" too many teams, obviously the hall and palmieri trades were big wins and have a lot of public perception in that, but he's typically good about his trades. At the time, they tend to make sense, and he seldom is seen as giving up too much. The one I'd argue he did was the Mirco Mueller trade, but overall, at the time of the trade, his deals are often seen very positively. The grabner trade was another not great one.
That being said, they certainly don't all work out. The Marjo trade seemed awesome at the time, felt like the devils got a steal. That didn't work at all as Marjo couldn't stay healthy, and while he was productive in the lineup, he never quite for in completely. Even the pk trade makes a ton of sense and seemed like great value. Sure, that was money related (the low return) but the devils had no problems with money even with him, so the return they gave up was more than worth it. But it's been not good.
But small deals like getting a second for Boyle, a 2 + 4 for Marjo, etc, are mostly positive. I don't know that he's a wizard or anything, but I'm confident in his ability to negotiate a trade.
Corey Pronman wrote leading up to the draft that Shero was very high on makar and had him going number one in his final mock draft to the devils. That draft was mostly all about Nico / Patrick at the top, but Pronman did put that possibility out there that they could go makar. Honestly? Wouldn't be surprised if that didn't happen just because the devils weren't able to trade down
