Classical historian Mary Beard writing for BBC

In the ancient world, the rich held themselves to very different standards from the poor. Not much has changed, argues classical historian Mary Beard. Low life in ancient Rome could be very low indeed.
There were gangs of ne'er-do-wells and down-and-outs who spent all night in cheap bars, drowning their sorrows. Apart from talk about the top chariot racers (the ancient equivalent of footballers), the only entertainment on offer was brawling and gambling.
They would sit hunched over their gaming tables, making horrible snorting sounds through their quivering nostrils.
(The Greeks and Romans seem to have been particularly sensitive to odd nasal noises. One pundit in the early 2nd Century - the aptly named Dio the Golden Mouth - gave a whole lecture to the people of the city of Tarsus, urging them to control their snorting. It must count as one of the most curious works of ancient literature to have come down to us.)
But his view of the behaviour of the underclass is the kind of fantasy that the rich have had about the poor ever since. My guess is that Ammianus had never actually set foot in an ordinary Roman bar and had never thought about the sheer illogicality of what he was claiming - if these guys really were desperately poor, how on earth could they afford to drink all night?