It's getting annoying now - surely we can agree that once unmasked it's fair game. Really guesses aren't spoilers either.
Indeed the irony of this show is they need the "detectives" to not be very good - knowledgeable enough to throw out some plausible names, but not guessing every single one at first sight.
Must say the only weakness, and perhaps it's because of the trickery required to keep it secret, is the unmasking. It just all feels a bit cheap.
It's great that everybody gets sarcasm.