It's interesting because this is the first time I've seen this sort of blacklist out in the open.
The first "FAQ" on Guestscan's FAQ page says...
Q. Why has no one done this before?
A. While the concept is simple, complying with all the legal aspects is complicated and time consuming. (Guestscan has taken two years to get it right.)
Well... they have done it before. I've heard about schemes like this operated by tour operators, hotels and even PRs, several times over the past couple of decades, but on enquiry they've always turned out to be 'informal sharing of information arrangements' that nobody ever knows anything about!
The reason is in the answer (above), which is accurate. The whole concept is a legal minefield and one that most travel companies and associations have been very reluctant to enter, even though there has always been a real demand for blacklist information. What tour operator, for example, wouldn't want to know that Mr X whose booking he is about to take, is a notorious serial complainer, who will almost certainly lodge a complaint plus claim on return from his holiday?
It looks, on the face of it, that Guestscan has overcome all the legal hurdles. I notice, for example that users have to become 'members' of the Guestscan Association and indemnify the Association against the "consequences" (legal?) of malicious reporting. So I hope it all works.
Oh, and if you are a journo, don't think you are exempt. I well remember a travel PR telling back in the early nineties how she kept and shared a blacklist of journos who behaved badly on press trips or failed to produce any copy.