Pliny NH 25.21: that Drusus among us, most illustrious of our tribunes of the people, who was cheered by all the commons standing before him but charged by the aristocrats with causing the Marsic War, was on the island of Anticyra cured of epilepsy by means of this medicine. For there it is very safe to take the drug because they add to it sesamoides, as I have already said. In Italy it is called veratrum.
Pliny NH 28.41: Drusus, tribune of the people, is reported to have drunk goat’s blood because he wished, by his pallor, to accuse his enemy Q. Caepio of having poisoned him, and so to arouse hatred against him.
Pliny NH 33.6: Also it was from a ring put up for sale by auction that the quarrel between Caepio and Drusus began which was the primary cause of the war with the allies and the disasters that sprang from it. Not even at that period did all members of the senate possess gold rings…
Pliny NH 33.13: Livius Drusus when holding the office of tribune of the plebs alloyed the silver with one-eighth part of bronze.
Pliny NH 33.50: His brother Allobrogicus was the first person who ever owned 1000 lbs. weight of silver, whereas Livius Drusus when tribune of the people had 10,000 lbs.
Excepting the first, all these passages suggest a tradition that casts Drusus as motivated by avarice and fundamentally dishonest.