Subtlety seems not to be in David Mackenzie’s repertoire. Following the explicit but tedious “Young Adam,” he’s come to America for this trite but self-important tale of a professional boy-toy in contemporary L.A. who finds himself hoist, as it were, on his own petard. Even the usually ebullient Ashton Kutcher comes across as unnaturally benumbed by the director’s dreary determination to tell a story he and writer Jason Dean Hall apparently think is powerful drama but in fact is nothing more than a wallow in old-fashioned melodrama. If ever a movie needed some irony, “Spread” is it. But all we get is a heavy-handed sermon.

Kutcher plays Nicki, a pretty but vacuous young fellow who initially tells us in vague voiceovers that he came to Los Angeles for the easy good life, a goal he’s pursued by coming on to rich older women in snazzy clubs and becoming their kept boy until he tires and moves on to the next conquest. As he traipses from hillside mansion to hillside mansion, he keeps his meager belongings at the shabby apartment of his only real friend, hapless Harry (Sebastian Star).

We watch Nicki as he moves in with still-attractive but needy Samantha (Anne Heche), who has a great pad, complete with pool, and a stack of credit cards, and who quickly gets accustomed to his being around and on call for sex, even though he soon proves he’s not exactly a one-woman kind of guy. You’d think Nicki would settle in for awhile, but it seems to take him no time at all to fall for Heather (Margarita Levieva), a hardboiled waitress, and begin pursuing her heedless of his occupational responsibilities. For the first time, you see, he’s suddenly smitten himself.

It should come as no surprise that it turns out Heather is his female counterpart, and his attempt to woo her away from that life leads to his own downfall as a male gigolo. Soon he finds himself wandering the streets bereft of friends (he’s alienated even Harry by his newfound insistence that strippers must be treated like human beings), ridiculed by girls he used to use and discard, and pawning his golf clubs and clothes just to pay for a cheap motel room. At one point he even makes a tearful phone call to his mother, who hangs up on him. In a final desperate act he follows Heather to New York City to persuade her to give up her wealthy fiance and marry him.

So “Spread” turns from a would-be stark expose of a young man (in every sense—the sex scenes are pretty racy) trying to get the good life through charm and his natural endowments into a maudlin story of redemption through love. Kutcher manages the first half of the story well enough—as he lies about the pool half-nude, his ennui seems genuine (though his clothes sense never does; he’s pretty badly dressed, the penchant for suspenders especially ill-considered). But as Nicki moves into morose lovesick phase, the actor seems out of his depth. Heche shows that she’s still buff but little more, but is nonetheless better than Levieva, whose brusqueness is ultimately rather tedious. A frog that serves as the star of the closing credit crawl outacts all the humans, in fact. Steven Poster’s crisp widescreen cinematography provides some lovely images, but can’t conceal the emptiness of it all.

Toward the close of the picture, Nicki tells Heather of her tony new life in the Big Apple, “This isn’t real. This is bulls**t.” He might as well be talking about the movie. It turns out that “Spread” is very thin.