ZZ Top fans have called Mescalero a return to form after 1999’s dire XXX. But what else could it be, really, when form is all the Top has ever had? The same pounding electro-blues, occasionally rousing itself to a leaden midtempo but usually as slow and regular in its groove and footwork as a drunk pacing past a couple of cops. The band strays only occasionally from being mildly iconic blues-metal weirdos concerned with whipping up a slightly dirty novelty number. These days, titles such as “Piece” and “Buck Nekkid” do little but leave you imagining how miserable all those strippers must be lumbering along to this stuff. If you’re at all familiar with ZZ Top, I guran-damn-tee you already know how these songs go. That said, Mescalero still has joy to be wrung. The title track, the snaky “What It Is Kid” and the instrumental “Crunchy” are all the kind of loopy-dumb blues that critics overpraise Los Lobos for, “Alley-Gator” could be the best track you skip over on the next Tom Waits album, and a cover of Lowell Fulson’s “Tramp” underscores how ZZ Top remains a reinterpretation of its original inspiration.