Especially used in (as) flash as a rat with a gold tooth, the phrase a rat with a gold tooth designates a person—usually a man—who, in spite of a superficial smartness, is untrustworthy.
In this phrase, the noun rat refers to a deceitful or disloyal man. The image is that, despite the gold tooth, a rat’s basic nature cannot change.
For example, Bill Deane used the phrase in the review of Vintage Pierpont (Sydney: Allen & Unwin, 1985), by Trevor Sykes—review published in The Canberra Times (Canberra, Australian Capital Territory) of Saturday 15th March 1986:
To Pierpont, cynicism and scepticism are indispensable for survival in the corporate financial jungle. […] He continues to refuse to suspend his disbelief at company annual reports and audit statements, accountants being regarded with only marginally less distrust than might be accorded a rat with a gold tooth.
These are, in chronological order, the earliest occurrences of the phrase a rat with a gold tooth that I have found:
1-: From the review of The Long-distance Search for the Great Australian Funnybone, a television programme broadcast on ABV-2 on Tuesday 18th July 1972—review by John Pinkney, published in The Age (Melbourne, Victoria) of Friday 21st July 1972:
The programme, which promised to define the antipodean sense of drollery, but wisely chickened out, was, largely, a delightful anthology of rural pub persiflage.
From singleted soil-tillers—so earthy they might have been uprooted from a nearby paddock—came country tales and sayings which had about them the smell of centuries.
For example, one drinker’s definition of a drover’s breakfast (“A leak and a look around”) was used—and credited as a hoary saw—by Lawson, in a story for the old Bulletin.
But old or recently minted, there was a pungency about the lines the drinkers delivered—their camera-nerves deadened by soothing lager.
“Dressed in this suit,” said one unaccustomedly sartorial laborer, “I feel I’m bungin’ on more side than a rat with a gold tooth.”
2-: From Ginger Meggs comes home, by the Australian television journalist Bill Peach (1935-2013), published in The Sun-Herald (Sydney, New South Wales) of Sunday 27th August 1978—Bill Peach told the story of Ginger Meggs, “Australia’s most enduring comic strip hero”:
There are two […] characters whose aim in life is to prevent Ginger having fun. One is Eddie Coogan, his arch rival for the affections of Min. Eddie is the ultimate lurk-man. He is always flush with money—money which one suspects the pestilential Coogan can only have acquired by foul means.
Eddie is as flash as a rat with a gold tooth. He patronises Ginger, heckles him, attempts at every turn to trip him up or do him down. And no trick is too filthy for the Coogan repertoire.
3-: From Clothes maketh the yachtsman, by Ron Saw, published in The Bulletin (Sydney, New South Wales) of Tuesday 31st October 1978:
“Are we,” asked the for’ard hand, “entertaining royalty aboard, or something?”
“Are we going ashore to a garden party, or perhaps a levee, at Government House?”
“Then would you mind telling me why you’re all dressed up like a pox-doctor’s clerk?”
I looked down at my clothing. I was wearing clean white shorts, white socks and blue deck-shoes, and a red shirt; not, I’d have said, an overstated ensemble; certainly not one to bear comparison with a pox-doctor’s clerk.
As far as I know I’ve never seen a pox-doctor’s clerk, but whenever I’ve thought about one, I’ve seen some sneak wearing a mauve suit and a tie-bar, with a stone in it, just below the knot of his tie, and probably a lot of Californian Poppy glazing the tops of his ears. Flash as a rat with a gold tooth.
4-: From The Australian slanguage: A look at what we say and how we say it (North Ryde, N.S.W.: Cassell Australia Limited, 1980), by Bill Hornadge (1918-2013):
Flash as a rat with a gold tooth.
5-: From Dubious value of our cultural landscape, by Maurice Dunlevy, published in The Canberra Times (Canberra, Australian Capital Territory) of Saturday 28th March 1981—here, the phrase is applied to two localities:
After I had read the arguments by Jeans and Spearritt last week that we should treat the cultural landscapes of New South Wales as an open air museum I set off last Saturday to test them.
In ‘The Open Air Museum’ (Allen and Unwin, 154pp., $18.95) D. N. Jeans and P. Spearritt argue that the evidence of our history lies not only in dusty tomes but in our landscapes.
Jeans and Spearritt argue it is time to put away aesthetic considerations and concentrate on cultural significance. It sounds fine in their book but I found it not nearly so impressive when surrounded by traffic lights, a colony of garden gnomes and the Winchcombe and Carson sheds.
Nor was the crass commercialism of Berrima very impressive. If the price of preservation must be the sale of knick-knacks to Sydney trendies, perhaps it is too high a price to pay. Berrima used to be a sleepy 19th-century village that survived into the 20th century, just as the Rocks used to be a delightfully grotty survival of the convict era. Now they’re both as flash as a rat with a gold tooth.