The only obvious cheat here is reading skills. Those who use it can easily find the following:
With that said, I have encountered some suspicious behavior: users of so-called ‘deck trackers’ or whatever having access to information that they shouldn’t (for instance, you shouldn’t see your opponent’s hand, as if it were your own, with any kind of ‘deck tracker’) or this bug, but this isn’t one of those instances.
PS It is also telling that, with so many people having participated, I’m the first one to point that pinned (!) topic out.