John Prine often sings like he’s doing nothing more urgent than chewing on a blade of grass while lazing away a mid-August afternoon. His laconic tone is deceptive, because he’s one of the most sharply observant storytellers the post-hippie folk-country scene has produced. Though In Spite of Ourselves includes only one Prine original — the ribald title song, in which the once-innocent Iris DeMent sings about the panty-sniffing rogue she can’t help but love — it’s full of Prine-worthy tales. The theme linking these honky-tonk standards and obscurities is fidelity, or the lack thereof, served up with a double shot of wry. The singer and his duet partners — including Grand Ole Opry giant Connie Smith, alt-country pioneer Emmylou Harris and current Music Row queen Trisha Yearwood — settle in comfortably against twangy backdrops that evoke Lefty Frizzell’s Nashville more than Shania Twain’s. Though his sidekicks are more technically gifted, Prine sounds like he knows the people in these songs personally: As he celebrates wife swapping on Onie Wheeler’s “Let’s Invite Them Over” and white-trash romance on Bobby Braddock’s “(We’re Not) The Jet Set,” he fairly twinkles with mischief.