It’s good to keep the old expression “you can’t judge a book by its cover” close at hand when evaluating a bunch of wingnuts like the Nuclear Boots.

The goofy trio didn’t exactly break the bank on the packaging for “Idiots in the City.” There they are on the cover, smug and ridiculous, sporting electric lime accessories to promote cheeky song titles like “Tie u Up.”

Something strange happens, however, when listening with such tempered expectations. Once you push “play,” nothing short of a garage-grunge miracle begins spilling out of the speakers.

Taut and well-planned, the three “Idiots” have come up with a beautifully purposeful set where lyrical cadence and band cohesion are anything but neglected.

Lynchpin Zeke Comparetto spits rhythmic pulses into the simplest of phrases, like “it’ll never be the same without you.” Then, when it’s just right, he unleashes an uncanny guitar phrase, always with a crafted beginning, middle and end.

The vocals on “Idiots in the City” come off like a snarly Tom Petty — rarely pretty, and never off the mark.

Check the infectious booty wiggling to be had in “Haddock,” where Bruce Merson and Miles Comparetto’s saucy rhythm section lifts bendy surf guitar for a full three blistering minutes.

Seekers of complex prog-rock need not apply here, as the Nuclear Boots carry the day with simple ambitions.

Some records get worse with subsequent listens, but not so with “Idiots in the City.”

Harnessing Strokes-ian focus, the Nuclear Boots and their cool detachment wear like trusty jeans.

Mike Olcott is a freelance writer who lives in Portland and Boston.