Tells are a vast area of poker.
It's not just the expressions and betting rhythm, it's also about wether the person is bluffing, playing a strong hand or looking like a bluffer as u play your strong hands.
And the most fun part is that when u try to read peoples tells, u have to know if this person knows how to imitate their own tells. I know some who can, me included.
It's just the matter of how well and how often.
In my opinion, one should change the way that one plays their strong hands and vary them between 'totally bluffing-look' and 'strong as ever-look'
When bluffing, I tend to use the strong play look, but if a person is able to read tells, I might use the conterbluff-bluff, where I bluff, but the person is getting my usual 'totally bluffing with a strong hand-look'.
Its fun, as more than once I've gotten a strong reader lay down their hand with this counter bluff bluff. Sometimes, if I misjudge the situation, I of course end up losing bit bigger, as the person calls instead of folding. In these cases, they have either smelled my counter maneuvre, or didnt even think about it, as I looked like a cleaar bluff..
It's difficult, I know.

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