Voters have been promised thousands of jobs and tens of millions of dollars in annual tax revenue if they support a proposal to open a southern Maine slots parlor. But before going into the voting booth, they ought to remember that they’ve heard this kind of thing before.

The Nov. 7 referendum guarantees only one thing – that Shawn Scott will get the exclusive right to develop a casino in York County. Scott’s is a familiar name in Maine. The multimillionaire was behind the 2003 initiative that added slot machines to a struggling horse track in Bangor, bringing Maine its first casino. Fourteen years later, Scott is back, with a proposal that casino backers say will create 2,165 permanent jobs and bring in $45 million in annual tax revenue.

If history is any guide, however, those figures are far from a sure thing. Look at the 2010 economic impact study on the then-proposed Oxford Casino, which predicted that the casino would yield 1,700 permanent jobs and $60 million in yearly tax revenue. State records show that Oxford Casino has produced only 400 jobs and $32 million in yearly tax revenue.

Asked to explain the discrepancy, economic analyst Clyde Barrow told the Maine Sunday Telegram that his firm’s study was based on plans for a much larger project than what was actually built in Oxford. But he also gave voters advice that they’d be smart to heed this time around: Be skeptical.

The Oxford Casino analysis was commissioned by a pro-casino group. So was the York casino analysis. That means these reports are essentially multipage advertisements that highlight the most optimistic data and downplay or leave out reasons to slow or stop the project.

And in this case, there are a lot of reasons for caution. For one thing, a massive casino is under construction in Boston that could pose serious competition for a casino in southern Maine. Then there’s the trail of lawsuits and allegations of deceptive practices that has long followed Scott, whose 2003 application to buy a slots license in Bangor was derailed after regulators scrutinized his businesses and associates, concluding that his companies “have demonstrated sloppy, if not irresponsible, financial management and accounting practices over several years.”

Most importantly, nothing in the measure that’s on the fall ballot requires Scott to follow through on the job-creation and tax revenue promises. And years of foot-dragging in Augusta have guaranteed that current Maine law won’t compel him to live up to his campaign’s rosy predictions. With this in mind, Maine voters should scrutinize the data in the York casino analysis and be wary of assuming that it accords with reality.