I think deception is fine if it's about what evidence they have. What isn't fine is deception about the the law and physical threats. It's one thing to say you have someone's prints at a crime scene hoping they confess, it's entirely different to threaten to kill their dog or say you aren't allowed to talk to a lawyer. The basis of our adversarial legal system is that the truth will emerge from a fair fight between the sides. Deception on the facts, but not the law or threats, seems to be balanced. There are other areas of the law that are not, but this one seems to check out.

Some potential tips are to stay calm while asserting your rights and ask for a lawyer. Record anything you can, even leaving an open 911 call if you feel your safety is in jeopardy. Ask for a supervisor. If you're being forced and physically threatened to comply with something like an unlawful search, say you only consent under protest (recording needed).