You always want to be very careful about lying. Only do it if you
know it isn't verifiable.
Lynch all Liars is a cornerstone of Mafia for good reason.
Because people are boring idiots?
I wouldn't really say that. Mafia's a really complex game.
When Scumhunting you're trying as hard as you can to find Scumtells, which are signs that someone's guilty. Scum need to lie in order to stay latent. I'd spend hours of active engagement and interrogation just to grasp a few deceitful lies or discrepancies. If someone makes a lie, and it's verified as a lie, I would jump on it immediately to try and unravel it as best I can.
As Town you can be very unboring. Let's say you like interrogating folks. Well, there's no cap on that. You can go nuts on it, taking it to as much of an extent as you want, while having fun at it, too. This goes for aggression, too. (Note that one can be aggressive and civil). When I'm looking for entertainment I tap into my aggressive side and do everything I can to yank out information and genuine reactions. I've caught nervous Scum and frustrated Townies that way. Basically what I'm trying to say is that you can do practically anything to have fun in this game. There are only a few restraints in Mafia.