“Oooh, honey, less is more,” the flamboyant hair stylist whispers, out of earshot, at Diana (Melissa McCarthy) as she bombs her head with hairspray and trowels on the eye shadow.

That’s never the case with McCarthy, the bawdy, rude, larger-than-life comic whose big movie break was “Bridesmaids.” She riffs, tosses back belts of booze and punches galore as the crass and crude title character in “Identity Thief.”

But “less is more” might have helped this cumbersome comedy that has Sandy, Jason Bateman’s mild-mannered office drone, trying to wrestle Diana across the country to save his job, clear his criminal and credit records, and make this opportunistic crook see the consequences of her actions.

It’s overstuffed with villains, from Sandy’s sneering, Ayn Rand-quoting boss (Jon Favreau) who greedily keeps all the company profits for himself, to the two thugs (Genesis Rodriguez and T.I.) chasing Diane for ripping them off, to those thugs’ imprisoned boss (Jonathan Banks) who wants Diana dead, to the skip tracer (Robert Patrick) determined to fetch her for his bail bondsman client.

There are car chases, rowdy sex romps in cheap hotels, and lots of scenes where Diana trots out her skills at lying, conning, stealing, copying credit cards and opening handcuffs.

While the filmmakers might have shot for “Midnight Run” but would have settled for “Due Date,” they wound up only achieving “Guilt Trip.” “Identity Thief” is sputtering long before that mid-movie moment when it turns all sentimental and goes off the rails.

Bateman, the guy America loves to see suffer, isn’t just the passive straight man here — probably a mistake as McCarthy, in her first lead role outside of a TV sitcom, tries too hard. Singing along to every song on the radio, trying to escape on foot (futile), punching those who get in her way in the throat, she sucks all the oxygen out of this thing even when she’s not straining to find an extra laugh in a scene. Bateman’s Sandy spends a lot of time being insulted over his “girl” name — “It’s UNI-sex” — and gets entirely too wise to Diane’s tricks too early on.

The way “Midnight Run” works is in one character underestimating the other. “Due Date’s” comedy is in the slow Robert Downey burn as we wait for the put-upon one to finally go off. Director Seth (“Horrible Bosses”) Gordon doesn’t get that.

There are some huge laughs in this. But making Sandy as testy as Diana, straight off, denies this road trip of its comic tension. So as much righteous fun as it is to see the woman who has stolen unisex Sandy’s name and credit and wrecked his life get clocked with a guitar, having it happen 13 minutes into the film robs “Identity Thief” of its punch.