The cause of his authority was not mere words, but, as Thucydides said, the opinion of his life and the honesty of the man, being conspicuously incorruptible and above bribes. And from greatness, [Pericles] made [Athens] the greatest and wealthiest city. [He] far surpassed kings and tyrants in power, some of whom made him the guardian of their sons, but he did not enrich his estate by a single drachma from what his father left him.
Αἰτία δ᾽ οὐχ ἡ τοῦ λόγου ψιλῶς δύναμις, ἀλλ᾽, ὡς Θουκυδίδης φησίν, ἡ περὶ τὸν βίον δόξα καὶ πίστις τοῦ ἀνδρός, ἀδωροτάτου περιφανῶς γενομένου καὶ χρημάτων κρείττονος, ὃς καὶ τὴν πόλιν ἐκ μεγάλης μεγίστην καὶ πλουσιωτάτην ποιήσας, καὶ γενόμενος δυνάμει πολλῶν βασιλέων καὶ τυράννων ὑπέρτερος, ὧν ἔνιοι καὶ ἐπίτροπον τοῖς υἱέσι διέθεντο ἐκεῖνον, μιᾷ δραχμῇ μείζονα τὴν οὐσίαν οὐκ ἐποίησεν ἧς ὁ πατὴρ αὐτῷ κατέλιπε.
Plutarch, Life of Pericles 15.5
There are always going to be accusations of impropriety and Pericles is no exception. We are told that Pericles was charged with dressing Athens in bangles and ornaments like a wanton woman (Plut. Per. 12.2), misappropriating money from allies to pay for building projects (Plut. Per. 12.1) and various forms of sexual impropriety (Plut. Per. 24; Athenaeus 12.45, 13.25), but these are for the most part slander from political opponents bitter about his power or mean jokes composed for the comic stage.
Plutarch here offers an explanation for why Athens flourished under the guidance of Pericles. Intelligence and presence help, but the fact that Pericles resisted using his position for personal, monetary gain was critical to Athens to becoming great. He might be onto something.