It’s a scam... but the guest editors are probably not to blame.
But they are, Brian, they are. By publishing in, or editing special issues of these journals, serious scholars lend their credibility to the garbage that comes along with it. I wish they wouldn't. As Dominik points out, there are many other options for open access publishing that won't bleed our universities dry. And for every story of rigorous peer review, there are two or three of quite the opposite.