lets say everyone plays by the book....then is +ev still +? or -ev

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is there EVER a "perfect play" in poker?
i mean i know it depends on situation, people, and many other things

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Poker is a game of imperfect information. Because of this, the "perfect" play is simply an unattainble truth that makes making the "best" play both possible and necessary. The "perfect" play in poker is the one you would make if you knew everybody's cards and exactly how they will react to your play and how to adjust accordingly. Because this information is never 100% available, it is necessary to make sacrifices in order to account for your uncertainties. Making the "imperfect" poker play is the one that is the closest that you can get to the perfect play given the information that you have collected up to date.

In response to the OP:
Even if everybody played by the book, consider Mike Caro's "Law of Least Tilt". He states that in a game filled with players of equal skill, the player that wins the most will be the player that tilts the least.