But now he has the perfect excuse to bask in the limelight and give free rein to his exuberant personality. He is running for mayor.
More than a few commentators have wondered how wise Las Vegas would be, given its already dubious reputation, to elect a mayor known as a "mob mouthpiece" and "barrister to butchers". The police are outraged that a man who spent years undermining their credibility might soon be in charge of them. The property developers who usually drive Las Vegas politics haven't given him a single significant endorsement.
But Oscar Goodman doesn't care. The people love him, he's soaring way ahead in the polls and stands a reasonable chance of clinching the race in Tuesday's primary without having to worry about a run-off.
His secret? Doing what he wants and telling it the way it is. Last week, on a campaign stop at a highly sceptical Chamber of Commerce, a jewel- laden female banker yelped as he shook her hand. "I'm sorry," he said with a big grin as he stared at a monster diamond on her ring finger, "I was having some trouble slipping it off." The room erupted in laughter.
Going against all received political wisdom, he has declared war on the property developers and threatened to impose hefty taxes on them to keep the runaway growth of the city's suburbs under control. He says the effort to reinvigorate Las Vegas's shoddy downtown "stinks", and calls the Fremont Street Experience - a new covered walkway over Binion's Horseshoe, the Golden Nugget, and other classic Vegas venues - a $110m dollar embarrassment resembling a giant construction toy.
So why is he running? "I love Las Vegas," he says. "This is not a cow town any more. It has a large population. The roads are in gridlock, the air is polluted, and our quality of life is threatened. It's time somebody did something about it."
Even at the best of times, there is nothing normal about Las Vegas politics. This is a town where candidates solicit contributions from gamblers, strip- club owners, boxing promoters, faded television stars and sozzled crooners still doing their bit to keep the tourists flooding in. A town where political business is essentially controlled by the big economic interests - gaming executives (once financed by the Mob, now buoyed by former junk- bond billionaires as well as more orthodox corporate investors) and property developers, who have turned the desert valley into the fastest-growing metropolitan area in the United States.
Even against this lurid background, though, Oscar Goodman - "the big O", as he is known - is something else. He'd call himself a populist, a man unafraid to go against Vegas's vested interests to fight for the city he loves ("My endorsements? My wife loves me very much.")
Others might see a more nuanced picture. In a town that likes to think it has shaken off the insidious grip of organised crime, here is a man who both reminds people of their dirty past and, perhaps, offers them hope for a new, cleaner future. After all, he may have been a mob lawyer, but federal prosecutors never showed a single link from the underworld to his clients, despite years of investigations, informant shakedowns and wiretaps on his home and office.
Mr Goodman came to Vegas in 1964, a newly qualified Philadelphia lawyer with, by his account, just $87 (pounds 55) in his pocket. His break came when a Canadian pornographer delivered $3,000 in cash to his office with a request to get his brother off a charge of transporting goods in a stolen vehicle. It was the first of many successful cases.
Meyer Lansky, the Mob's financial whiz, escaped standing trial on charges of organising a casino-skimming racket after Mr Goodman successfully argued that his health wasn't up to it. Tony Spilotro, depicted by Joe Pesci in the Martin Scorsese movie Casino as the Mob's Vegas enforcer and a near-psychopathic killer, stayed out of jail in the 17 years he was represented by Mr Goodman, despite being accused of some two-dozen murders.
Mr Goodman played a cameo part in Casino, as himself. "That was a mistake," he says now. "The overall tenor of the movie was right, but they misrepresented my clients." Clients, it must be said, to whom he remains remarkably faithful, even though many are dead. Spilotro, for example, was beaten with baseball bats and buried alive in an Indiana cornfield in 1986. "I take offence when people call him a bad guy," he says. "Shame on them when they couldn't convict him."
If Mr Goodman remains a credible independent voice, it is because he is clearly not in it for the money - his law practice has made him a multi- millionaire - or, at the age of 59, for long-term career advancement. "I think he wants to be remembered as something other than a mob lawyer," opines John L Smith, Vegas's savviest political commentator. "He doesn't want to go down as the guy whose clients put body parts in the backs of cars. This is his chance to do something positive."