Ventriloquist, Harley, and Scarecrow being the main victims of Lyle Bolton acted as proof of his sadism, which one can interpret that he selected vulnerable prisoners in Arkham instead of more ruthless villains (Killer Croc and Joker for example) to abuse them easily rather than his self-professed "tough-on-crime" beliefs.
This, therefore, would make Bolton a Dirty Coward.
Lock-Up's mask only exposes his eyes, whereas Batman's cowl only exposes the mouth. This is to symbolize that Batman is much more open to try and reason with Gotham's criminals if he has the chance, whereas Lock-Up will indiscriminately go after anyone without even thinking about trying to reason with them.
