1) Cleverly cagy 2) Cleverly evasive 3) Deceptive 4) Puzzling 5) Skillfully evasive 6) Slippery as an eel 
• (a.) Tending to elude or deceive; evasive; fraudulent; fallacious; deceitful; deceptive.
E·lu'so·ry adjective [ Late Latin elusorius .] Tending to elude or deceive; evasive; fraudulent; fallacious; deceitful; deceptive. -- 
elusory 1. Tending to elude (a danger, argument, law, etc.); of the nature of an evasion or subterfuge. 2. As an object of thought; that which eludes the mental grasp; that which one cannot 'get hold of'.