On tour, Leon Redbone can be found at folk festivals. In record stores, you’re more likely to find him in the rock section (where he has no business) than in either blues or jazz, which seem more plausible. Redbone plays the music of the rural South of the ’20s and ’30s—a time and place when the difference between blues, jazz, and even old-time country was a lot fuzzier than it is today. While this mixture of the three has earned him a loyal following since his first appearance on Saturday Night Live 20 years ago, it has also gotten him gigs on Madison Avenue. (He sings the All detergent commercial with the flying stain.) Redbone has never really found favor with blues or jazz purists who are just too serious for his ambiguity, his willingness to play novelty tunes, and, possibly, his voice (which sounds like Foghorn Leghorn’s after 30 years of dedicated bourbon drinking). But if you liked the Crumb soundtrack and suspect that there’s a more gentlemanly side to early blues than Robert Johnson, then Redbone is a great introduction and possibly the best practitioner working today. With W.C. Spencer at 7:30 p.m. at the Birchmere, 3701 Mount Vernon Ave., Alexandria. $17.50. (703) 549-7500. (Jandos Rothstein)