Owing to our implementation of a close variant of the Gieseking's indexes, we show that a semilocal exchange-correlation approximation such as PBE may create the illusion of modeling the emergence of plasmon bands in noble metal nanoclusters while the given absorption bands lack of any plasmon-like character. In other words, such an approximation is prone to give the correct answer for the wrong reasons. We attribute this error to the low energy gap between the (n -