I didn't like Asia Rooms. They presented me with some options, I selected one, provided my hotel, dates and CC details, and the response was "thanks, we'll check whether that is available and get back to you within 24 hours". If there was any doubt, why present the option? I don't think we're talking difficult IT here.
Anyway, it wasn't available, turned out to be a good thing because I found a much better option, but the killer was that the $1000 or so that the booking would have cost was 'deducted' from my CC and the funds unavailable to me for around a week.
I have subsequently found this is alleged to be a common practice (called CC blocking?), by which these companies ensure they get their share of your credit limit, should you be inclined to try and rack up debts way beyond your limit.
Maybe they all do this?
Edited to add: The better option was a deal via a specific hotel's website