It's meaningless marketing speak, perpetuated by private sellers. I think if an actual guitar company used that term to pimp its wares, it'd be laughed out of the industry. At the very least, it should fire its copywriter. That said, my guess is that a lot of people who make the claim that PRSs have no "mojo" do so because they're less than thrilled with the sound of the proprietary pickups PRS insists on using. Doubt it has a whole lot to do with the resonance of the wood and whatnot.