I don't even think that was the most scandalous of its era, let alone all history. In my opinion, for that era at least, it's Clodius being discovered at Caesar's house in 62 at the festival of the Bona Dea - for women only, men were forbidden from its observation - in drag, asking for Caesar's wife presumably because he wanted to smash, at the time when Caesar himself was pontifex maximus and was the high priest of Roman religion. That's violating the biggest taboos in their culture:
- a man dressing as a woman
- a man violating a solemn and sacred religious ceremony that was only for women, on pain of death
- a man attempting to sleep with another person's wife
- the woman in question was married to the highest religious authority in the empire and she was conducting said religious ceremony when this happened
- and to top it all off, when Clodius was put on trial on the charges of blasphemy and adultery and incest (the last one unrelated to this incident, but added to the prosecution case anyway), he was acquitted by a margin of three jury votes, and everybody knew it was because Crassus, the richest man in the Roman world, had bribed the jury to get him acquitted
Bona Dea - Wikipedia
What this summary doesn't mention is that Clodius was like the Brad Pitt combined with Al Capone combined with JFK of his day. He was a scion of by far the greatest family in Roman history, the Claudii, who had produced dozens and dozens of consuls. And he was also considered the best looking man in the city
Because of his social status, his looks, and his extravagant playboy lifestyle, Clodius was the man who got the most attention from people in his era, more so than Caesar or Antony. Clodius was also a gangster who commanded the biggest and toughest gang in the city, and due to his gang power he was also a leading politician.
For all these reasons, even people who were apolitical were interested in Clodius and what he was doing, where they may not have been interested in Caesar and Antony. That's why I believe that any scandal involving him was just far bigger than anything about Caesar and Antony; they never had juice with the people like Clodius did. Sure they had much more political and military power, but put it this way, if there were gossip magazines and paparazzi and things like that in the Roman world, they would have spent far more time on Clodius than anybody else.