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 straitjacket.

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.

There are even moments that suggest Gibbons' songwriting chops might be returning, such as the closing "Liquor," the rampaging instrumental "Crunchy," and the lithe "What Would You Do." On these cuts, along with a cover of Lowell Fulson's "Tramp," ZZ Top sound like a worthy veteran act, returning to their strengths and building on them.

Unfortunately, that's four songs on an overlong 17-track album (including an uncredited closing cover of "As Time Goes By," hidden after "Liquor" -- as most uncredited covers of "As Time Goes By" are, I suppose), and the rest of the record is pretty much devoted to by-the-books latter-day ZZ Top, relying too much on overly polished sound and familiar form, not gutbucket hooks and dirty grooves.

What's frustrating is that those aforementioned cuts prove that the boys could still turn out a really cool, modernistic roadhouse blues-rock album, if only they had a good editor or producer.

Left to their own devices, they repeat their same mistakes and wind up with a record that's pretty damn near the same as their other RCA platters.