but what about the situation where YOU say "i dont have scrambles/DREs" and in reality you do?
thats directly lying, not answering an opponents question, what do you think of that?
"How many prizes do you have left?"
"I have 4"
"...But I can see with my eyes that there's 5 left."
"Yeah, so?"
"You just let me attack with a scramble attached when I couldn't have..."
"Well then, you made an illegal move."
That's lying about public information. see the result? Illegal move?
Forcing an illegal move should be penalized.
Now... Say one player is considering playing Crystal Beach. There is a Battle Frontier already in play, and replacing it with Crystal Beach would allow their opponent to energy draw with Delcatty. Of course, for all the Crystal Beach player knows, their opponent might be able to win without need of drawing extra cards. So they ask:
"Do you have a DRE in your hand?"
"Yep."
"Okay, I'll play the Crystal Beach to counter it."
"Sure, why not. It doesn't matter since I don't actually have one in hand anyways. BTW, you just got rid of that Battle Frontier in play, which allows my Delcatty to energy draw now."
"Say what?! You lied to me!"
Do you see any moves that aren't legal within the game system? Any damage to the game state? I don't. Sure, the person got manipulated into an undesirable move. But playing Crystal Beach
does not break any rules, as opposed to the previous deception, where an attack was made, and possibly a prize drawn, that was not possible.
In summary: Public Knowledge being lied about should be penalized, because there ARE card effects that depend on Public Knowledge, and deceptions to force the opponent to break the rules should not be permissible. However, there is nothing dependant on Private Knowledge without forcing that knowledge to become public (see my Milotic d example in an earlier post), thus with no capacity for Private Knowledge causing an illegal move, there's no substantial grounds to disallow it.