A Comm for Historymemes

It's not a bad interpretation, honestly. I hold that the accusations about Tiberius are possible and plausible, but also that by the rumormongers' own admissions, the whole reason he retired to a private island was to forestall any attempts at communication with the outside world, which calls any stories of his debauchery (which are almost all centered on said period of private seclusion) into question.

Tiberius being bitter, cynical, and generally not personable (such as being called tristissimus hominum, or calling the Senate 'men fit to be slaves' in disgust at them resisting a greater role in ruling the Empire) undoubtedly fed any negative feelings at the time. Capping it all off with treason trials at the end of his reign probably didn't help any eagerly-passed-along distortions of the truth either.

"Dull bureaucrat is secretly a freak beneath the sheets" is always possible, but so is "Sadboi just wants to be left alone and be sad in peace"