The central appeal of the Isobel Campbell-Mark Lanegan pairing is simple. Their contrasting singing styles — hers is soft and sweet; his is gruff and gravelly — mesh with surprisingly effective results, like olive oil and vinegar or MSNBC pundits Rachel Maddow and Pat Buchanan. What Sunday at Devil Dirt isn't is anything like the bands that former Screaming Trees frontman Lanegan and ex-Belle & Sebastian cellist/backing vocalist Campbell are primarily known for. Instead of psychedelic grunge or whimsical pop, it's a collection of slow, often dark, Leonard Cohen-esque folk songs. As with their first effort, 2006's Ballad of the Broken Seas, Campbell writes most of the songs while Lanegan does the heavy vocal lifting. But they're a duo for a reason, and the best songs on the album are the ones in which the two work closely in tandem, like the menacingly seductive lead single "Come On Over, Turn Me On" and "Who Built the Road," in which they trade verses then join forces on the choruses. Too many tracks sound more like Mark Lanegan "featuring" Isobel Campbell, such as "The Flame That Burns," a fair but ultimately hollow Tom Waits sound-alike. The lyrics match the music well, fitting in perfectly with the bygone era Campbell and Lanegan successfully evoke, but it lacks genuine emotional depth, alternating between the manufactured moodiness of "The Raven" and the saccharine wistfulness of album closer "Sally Don't You Cry." Despite some lovely arrangements and commanding performances from both singers throughout, it's not much more than a well-executed pastiche of a timeless style — highly listenable, but not entirely memorable.