OK, that situation from PokeDad is sickening and wrong, so I dont want to go into that, but here's what I want to ask the morale knights.
Why should I not lie about the contents of my deck, if my opponent doesnt know its contents, considering my deck is personal? If I feel like saying "I might have Card X in my deck", then whats keeping me from that? Minor mind games are part of this game after all. There's a fine line between bluffing and intimidating.
The way I see it, theres nothing wrong with bluffing. It causes your opponent to carefully reconsider and maybe make an error. I've been able to get my opponent to retreat their active poke for Absol to empty my hand by saying I had a fistful of trainers, while in reality, I held 2 Claydol and a slew of energy. Would that be called wrong? No, he believed me, so he made the error of doing so. Never did I show my hand, after all.
Anything that is in the game at that point and thus should be known by the opponent (That is: Cards in play, Cards in discard, How many cards in hand), one shouldn't lie about. If I play Copycat and you tell me you have 7 rather as 9 cards in hand, thats wrong. But what I have in hand is NOT common knowledge, only I know. Why shouldn't I use that information as a bluff, I ask?
Long story short; whats wrong with some little mind tricks if you're "revealing" things about what your opponent shouldnt know anyway?