All that good will Melissa McCarthy had after “Bridesmaids”? Completely undone by “Identity Thief,” an obnoxious comedy made worse by obnoxious sentimentality. Unfunny, predictable, and vulgar, it’s the generic equivalent of a Judd Apatow movie. As always, you get what you pay for.

Unless, of course, fat ladies rubbing their crotches and braying like mules is your idea of comedy gold, in which case, here’s your swill of the week. Jason Bateman, trying manfully to hold on to his dignity, plays Sandy Patterson, a Denver corporate drone with a pregnant wife (Amanda Peet) and two little girls (sisters Mary-Charles and Maggie Elizabeth Jones). Mr. Average, in other words. McCarthy is Diana, a cheerful sociopath who smooth-talks Sandy out of his credit information over the phone and goes on a Florida shopping spree that ends up with the cops at her victim’s door.