One thing about the Bayushi Manipulator's mastery ability, thinking in game-world terms (not GM/Player interaction but really as what Rokugani people may think), is that it can also be a powerful deterrent. It may be a "secret" technique, but after some time of other clans' samurai being trapped and burnt by high ranking Scorpions using this ability, knowledgeable courtiers will think twice before attempting to exploit a perceived disadvantage in a Scorpion!
"Ok, I am pretty sure that Bayushi Katsuo is an alcoholic... but my sensei was also persuaded that he was deaf in one ear and tried to play this to his advantage when spreading a rumor behind his back, and this backfired badly! So do I really want to bring up the topic of shameful inebriated behavior in an attempt to catch him off guard, or am I being fooled?"
So a GM may or may not have the NPCs fall into the trap laid by the technique... but if they chose not to, there should also be instances where a real disadvantage that could have been exploited will be left unused because... "who knows with those **** Scorpions".