well it’s really difficult. Because one one hand, someone could have legit evidence against someone and they could be telling the truth but on the other hand they might be an executioner or mafia framing someone.
The real thing you need to look at is how well the role can be proved.
some tips are if a lookout claims someone visited a dead person, you should ask if anyone else visited the dead person. if they say nobody else but it turns out you or someone else did, they are lying.