Picking up on how players breathe can be a very big tell. For example, if you notice a sudden change in how they are breathing, maybe by their chest or if you can hear it, they probably made their hand. If they suddenly start heaving and their chest is expanding more than it was, this is them being unable to control their body language out of excitement. Now, if that player was bluffing, he probably would not be breathing at all!
In the same regard to tapping their fingers or shaking their leg, if you notice a player freeze up, it is because they are bluffing. If you hear them hum or whistle, and continue to whistle even though it looks like you will call, they are content with that because they want you to. But if they stop, it is because they are nervous and don’t want a call.
“Pokerclack” is a word that Caro himself invented which means a noise someone makes when trying to convey sadness. This can be a sigh, or their tone of voice, and you always want to be looking out for this. There is no reason so anything to emphasize how they say “I bet” or “I raise” unless they are trying to fool you. They are trying to sound sad so you will call. One of Caro’s final laws is “Don’t call pokerclack.”
If your opponents ever acts or sounds sad, he has a big hand. “Beware of sighs and sounds of sorrow.”