One must give a stern warning to those who wish to be extra pious and check the Lulab to see if the head is closed. While they are checking, they end up splitting the leaves of the seller's Lulab. As a result, they cause damages to the seller and, effectively, steal from him.
One might think that, on the contrary, it is a meritorious act to be meticulous and thoroughly check the Lulab. In fact, one who causes damage to the Lulab and, by extension, the seller, loses more than he gains.
A Lulab that is fully closed is considered to be the the choicest way of performing the commandment, however, it is not a strict requirement. Stealing, on the other hand, is a Torah prohibition. As such, when a person checks the Lulab, he must be extremely careful not to damage it. If he does, he must pay the vendor.
(See Maamar Mordekhai [Eliyahu], Haggim, 52:41)
Sukkoth, Succot, Sukkot, Succos, Lulav, Etrog, split Lulav, Lulab