Ever since ZZ Top signed with RCA, they fitfully tried to break free of the synthesized blues that once was their savior but quickly became a straightjacket. Like any addict, it was hard for them to quit that processed, sequenced sound cold turkey, so they weaned themselves off the robo-boogie, sometimes relapsing and adding too many synths to mix, other times breaking loose with some credible boogie. Apart from the dreadful misstep of 1999's XXX, they showed signs of life on all their RCA albums, and their fourth, 2003's long-delayed Mescalero, is no exception to the rule. Billy Gibbons' fat guitar tone really has some presence here, at least on some of the album, and there are enough rhythm tracks not performed to a didactic click track to provide some real swing.