Like many a gambling movie, “Lay the Favorite” is peppered with gambler slang, starting with the title.

But here’s movie slang that works just as well.

“On the nose,” as in casting Bruce Willis as Dink, a Vegas sports gambler whose sophisticated operation is designed to track and manipulate the various casino’s odds on an event.

“On the nose” refers to Vince Vaughn as Rosie, a manic, motor-mouthed devil-may-care New York bookie who works just outside of the law.

Equally on the nose? Casting Joshua (“Dawson’s Creek”) Jackson as a straight-arrow journalist boyfriend.

And “casting against type?” That would be Rebecca (“Vicky Cristina Barcelona”) Hall as a Southern-fried sexpot. Beth is a “private dancer” from Tallahassee who packs up her boots, tube tops and Daisy Dukes and flees to Vegas with dreams of being a – wait for it – cocktail waitress.

Generally, you don’t make serious coin as a gambler by laying the favorite. And casting on the nose generally means you’re playing it too safe, betting that the audience won’t mind the lack of surprises.

Of course, when you cast the normally prim and smart Hall as a seemingly naive “good girl” who quits her dirty dancing only to instantly throw herself at her much-older married boss (Dink), you’re asking for trouble.

Not that “Lay the Favorite” is totally her fault. The script, based on a gambling memoir by Beth Raymer, can’t make up its mind who Beth is. She’s Florida Panhandle Southern – without an accent. She’s clueless, but supposedly some sort of numbers savant. She’s innocent. Until you take a look at what she wears, day and night, and the brazen moves she puts on Dink, who is married to the jealous drunk Tulip (Catherine Zeta-Jones).

Stephen Frears (“The Grifters,” “High Fidelity,” “The Queen”) never finds the sweet spot, never gives us a taste of joy of discovering this lucrative new line of work (Beth makes bets, delivers cash to cover them, etc.), the giddy highs of a winning streak, the misery of a losing one, the fear of going bust or getting busted.

Hall, as easy on the eyes as she is in these tarty get-ups, fails to figure out if Beth was an innocent who wised up in the racket, or if she’s been a petty thief all along. And she and the script she struggles over don’t make that a hold card we’re the least bit interested in gambling on.