holy forget im bad at brown townyzing faces
A character averting their eyes away always means you have to either use force (Bad Cop) or call them out on a lie. You can't just rely on their faces though you have to be paying attention to the case story, evidence, and make sure you have everything before going into an interrogation. Sometimes lying characters will have straight faces which is why you need to be aware of the small details and catch them on it.
Also use force if someone is withholding information, while they're technically not lying it still information you need and they surely have. It's one of the reasons why Doubt isn't a good name for the action.
There are a few dumb moments where other pieces of evidence would prove the same point but is marked as wrong. Other than that the system is pretty consistent thoughout the game so you'll get a hang of it the sooner you go on