I think it's simpler than that: people get better at things with practice.

Werewolf isn't like poker where people typically try to conceal their emotions and leak nothing; instead you're trying to act like you're on the Villager team regardless of whether you actually are.

Remember, being a good liar means you can sniff out a lie too. It's not a terrible skill to teach if it can be wielded for good.

Maybe a mafia style game would be more suitable where both sides are played.