There’s the makings of a nasty satire of modern American materialism in “The Joneses,” but in the end writer-director Derrick Borte proves not to have the courage of his cynicism, and the movie goes soft, squishy and even—heaven help us—preachy. It winds up a cautionary tale potential viewers need to be warned against.

The premise involves stealth marketing, in the form of inserting a phony family into a well-to-do community to encourage their neighbors to want the new products they ostentatiously “model.” The false clan in this case is “dad” Steve (David Duchovny), “mom” Kate (Demi Moore), “daughter” Jenn (Amber Heard) and “son” Mick (Ben Hollingsworth). Under the direction of their company handler KC (Lauren Hutton), they make friends in the local community, whose desire to buy gold clubs, cell phones, clothes, cars and other baubles is fed by seeing their perfect new buddies using them with such pleasure. For a while the scheme goes swimmingly, and Borte and his troupe extract some snarky fun from the false family’s success in pushing gadgets onto the increasingly lustful locals, particularly Larry (Gary Cole) and Summer (Glenne Headly), the couple next door.

But it’s not long before the moralistic messages start pouring in. Steve, a newcomer to the scheme—an ex-golf pro turned car salesman—begins to have doubts, especially since he’s developing real feelings for Kate, the veteran who wants to top the sales team. Mick makes a blunder not only by making alcohol available to minors, but by coming on to the wrong person, in the process revealing a secret that’s been telegraphed well in advance. And nymphomaniac Jenn takes up with the husband of a rich local woman, assuming—wrongly, of course—that he’ll leave his wife for her.

The most heavy-handed moral, however, involves Larry, who goes so deeply into debt trying to “keep up” with Dave that he sees no way out. His tragic end leads guilt-wracked Steve to confess the whole charade, bring down the wrath of the community on his head. The only question is whether he’ll be able to persuade Kate to abandon the sleazy business and join him in the real world. Given the way the plot’s developed, what do you think her decision will be?

“The Joneses” is handsomely appointed, and Yaron Orbach’s cinematography sets off the culture on conspicuous consumption with considerable visual elegance. And the cast is game. Duchovny’s hangdog charm is a strong asset, and Moore springs back from the pathetic “Happy Tears” as the hard-nosed Kate, though she stumbles somewhat when she goes soft. The youngsters are fine, too, though their plot thread goes too far into melodramatic territory for either of them to pull it off. Hutton is icily businesslike, but Cole and Headly plays things rather broadly.

The central problem with “The Joneses” is that ultimately it chickens out in its attack on predatory marketing practices, turning into something very like suburban soap opera. This isn’t a tale that invites a feel-good ending, but that’s what Borte tries to contrive for it. The opportunity for salty satire is exchanged for a saccharine conclusion, and that’s a pity.