POP MUSIC REVIEW : ZZ Top Puts Its Own Spin on the Blues : The Texas power trio’s sold-out Forum show was tacky, trashy . . . and enormously entertaining.

Every form of music has its own unique avenues of pretentiousness, and for those predestined to play the blues, artificial austerity is probably the ultimate temptation.

ZZ Top has never had a problem with this.

Together for more than two decades, and packing ‘em into arenas for three-quarters of that time, the Texas power trio has never been too proud, too afraid, too reverential or too uncommercial to weave pop hooks into its blues-rock boogie or even to experiment with synthesizers and drum programming. On stage, live cattle and laser beams have been the band’s showy hallmarks over the years. It ain’t Howlin’ Wolf--or Robert Cray, for that matter.

Yet the essential primacy of the music has remained, somehow, almost unsullied, as influential on today’s generation of metal and hard-rock bands as ZZ Top was influenced by the roots music of Memphis and the Delta.

It takes a good deal of humor and self-assurance to call your album “Recycler,” or to set your show in a junkyard, both of which ZZ Top has done this fall. These thematic riffs were quite apropos for the show seen at the sold-out Forum on Sunday (the first of two nights there)--trashy, tacky, old-hat and enormously entertaining as it was.

There were no cows or snakes on stage this time, but rather a whole series of hydraulic magic tricks. Near the climax, a giant set of overhead metallic jaws came down and appeared to snatch guitarist Billy Gibbons and bassist Dusty Hill up, then dumped their apparently lifeless forms into a trash compactor.

A huge magnet did the same with a replica of drummer Frank Beard’s form. They all emerged unscathed--wearing new “Sharp Dressed Man” suits, in fact--driving severely compressed autos. Scrap metal, indeed.

The compact(ed) car that is ZZ Top’s pop version of the blues came through in ship-shape, stage magic or no magic. Some of Beard’s drums are electronic these days, and even on an acoustic kit, the sorts of rhythms the trio favors now are mechanical-sounding, chugging, mid- to fast-tempo.

Otherwise, it’s guitar business as usual, with the same kind of subtle, dumb double-entendres the group was putting out 15 years ago. It’s loud, lowbrow rock, done archly enough that effete snobs can like it too.

They do their best to make this all look easy. Gibbons and Hill, looking completely interchangeable with identical shades, hats, long coats and long beards, did some minimal visual choreography, the most elaborate of which was a Chuck Berry-like step toward each other on facing conveyor belts each moving backward--as if to say, “Why should we learn to moonwalk when we have machinery to help us?”

Effortless this isn’t, though. Like the “Christine”-like demolished car in the stage set that occasionally revved up and finally threw itself off its pile at show’s end, there’s still a lot of life left in oldies that the trio could just as easily walk through.

These blasts from the past were as unexpected as “Jesus Left Chicago,” an excursion back into hardcore blues, or as predictable and still radio-saturating as “La Grange,” which built to a hammering climax of guitar triplets and double-time triplets on Beard’s double-bass drums that was invigoratingly effective. Gibbons’ nimble-fingered burst of notes at the climax of the slow “Blue Jean Blues” was genuinely funny, not just proficient.

ZZ Top’s time-tested approach would be impressive with or without the big, expensive circus of effects they always drag along. But you’d have to be a pretty sour purist to begrudge them or the fans said show.