The current success of British pop-metal tricksters the Darkness has led heavy rock to a rediscovery of its great bipolar talent for being dead serious and seriously tongue-in-cheek. But how is a fan to know the difference? What rock is clowning fun and what is an earnest statement? As a guide, I've rated these recent heavy rock releases on a scale of what's really serious and what is not very serious at all.

Eagles of Death Metal, 'Death by Sexy' Not easy like the Eagles or harsh like death metal, instead, this vanity project from Queens of the Stone Age frontman Josh Homme swaggers with a goofy punkabilly power groove. Mostly, it's disposable cheese whiz for the turn-'n'-burn millennium. At other times, it's the best Rolling Stones music of the last 25 years. Goof factor: Next time, expect a disco-folktronica version of the Bee Gees' "I Started a Joke."

Tool, '10,000 Days' Surely, the title is a reference to what it feels like listening to this über-serious, slow-burning, prog-metal math problem. Even playing with the 3-D glasses that are attached to the packaging is a chore. Tool are brainy and precise, yes, with dense nuggets of riffs and jams, but they wholly lack wit and flow. Goof factor: As stone-faced, stiff and sober as a face on Mt. Rushmore.

Wolfmother, 'Wolfmother' From the opening yelp, Wolfmother play an intoxicating and perfect marriage of Sabbath cement slabbage and Zeppelin bucolic airiness. Then they break the magic by echoing Styx, the Beatles and Boston. Still, these Aussies know the Bonham stomp, and I believe the flute solo on "Witchcraft" is actually meant in earnest. Goof factor: The gods just tapped another keg.

Pearl Jam, 'Pearl Jam' Seattle grunge veterans wait 15 years and 10-plus albums into their career to finally release a self-titled disc? Now that's funny. Except that their second (and best) album Vs. was already originally self-titled anyway. Here, the true guitar-slinging Pearl Jam are playful, questing, searing, ready to forgive and let go. Goof factor: Two-thirds heart on the sleeve, one-sixth chip on the shoulder, one-sixth Cheshire Cat grin.

Danko Jones, 'Sleep Is the Enemy' This razor-edged, rough-rhythm Canadian pop-punk band and their energy-drink frontman share the same name. They've been called a cross between AC/DC and Mötley Crüe, but with their twitching neo-new wave, accusatory stance and buzzing guitar blast, they're more like a rough mix of Ratt and Graham Parker. Goof factor: Party like it's 1979, dammit!

Def Leppard, 'Yeah!' After years of irrelevance, the hair-metal titans emerge with a covers' disc that acts proud to be part of a trend that's not even happening. This tribute to '70s British glam apes its content, which includes diverse classic rock; their take on Free's "Little Bit of Love" is surprisingly inspirational. Goof factor: Is KISS' classic album Destroyer a piece of art or mere product? Discuss.

Atreyu, 'A Death Grip on Yesterday' Emo-metal? Atreyu deal in metal essentials like melodic guitar riffs, growling vocals and chunky drive, as well as emo essentials like call-and-response, retreat and confession. But in this well-done bid for greater commercial appeal, who are they? Goof factor: Their last album cover featured a bikini babe as a vampire. That was a metaphor, not a joke. This album cover features someone on fire.

Boris, 'Pink' When this Japanese noise-spazz power trio are gauzy and pile-driving, I fondly remember the last garage metal band I played in. Sometimes, I fantasize that this guitar squall is a type of jazz. When their gauzy pile-driving gets transcendent, I let myself release and dream. Goof factor: Why did the headbangers and shoegazers cross the road? 'Cuz, dude: Fucking Boris were playing on the other side!

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