It would never be rational to be irrational. In Rational Actor Theory, a rational actor is goal-oriented, reflective and consistent. If you act irrationally, you will not achieve one of these goals.
However, there is nothing which prevents a player from choosing to act in a way that appears irrational because they perceive a long term benefit to others perceiving that apparent irrationality. This would qualify as rational thought. The phrase for this is "there is method to my madness."
The uncertainty about players would be most likely incorporated into the reflective side. If it is clear that the other players are not being affected by your apparent irrationality, and you do not believe you are going to be able to sell it any better than you already had, then it is irrational to continue acting apparently irrational. You would either no longer be goal-oriented or you would no longer be reflecting enough to realize that your actions were not accomplishing the goals.