Ever since their biggest hit song, “Drive,” alternative rock band Incubus has been attached — some say shackled — to a “haunting mass appeal.” Unfortunately, their music is only haunting because it darkly lingers longer than it should. It’s the “mass appeal” — that gushing spring of mediocrity — from which all problems flow, especially in their sixth and latest album, “Light Grenades.”

Characterized by unimpressive lyrics attached to 14 tracks of varyingly underwhelming music, “Light Grenades” might sound slightly different than the band’s past releases, but it’s nothing new in the realm of alternative rock.

Still, a few singles from the album earn their place on the myspace.com pages of depressed teenagers who think they like indie music. “Anna Molly,” appearing both in electric and acoustic form on the album, calls forth memories of earlier Incubus favorites like “Pardon Me.” The acoustic version packs more punch since it features Brandon Boyd’s voice unfettered by noisy accompaniment. Still, it’s hard to forgive the song’s unsubtle, presumptuous title (“Anna Molly” = anomaly).

Incubus could surely use some extra help naming not just songs but their albums, too. Discordant to the point of supreme frustration, the song “Light Grenades” might be the worst track on the entire album when it should be one of the best, considering its title-track status. Crazy techno-sounds and rambling chords bounce off each other like a pile of ADHD kids crammed on a trampoline, producing a ruptured sound that the other melancholy tunes thankfully lack. Furthermore, the random combination of those two words (“light” and “grenades,” for those who’ve lost track) seems to imply a certain levity, or a distinct brilliance (given the double meaning of “light”) that the rest of the album doesn’t live up to.

Instead, as is to be expected, “Light Grenades” sheds melancholy and disillusionment like it were going out of style. The repetition of the word “dying” in the song “Oil and Water” marks the height of the band’s obsession with darkness and despair, and interspersed attempts to liven things up — like “Light Grenades” — feel oddly out of place.

And “Light Grenades” forces us to endure not just stereotypical melancholy but also scientific inaccuracy. In the song “Diamonds and Coal,” Boyd mistakenly wails that “diamonds start as coal.” That, of course, isn’t true. Yes, both diamonds and coal (or graphite) are carbonic allotropes, but they are free to form independently of each other, depending usually on the amount of pressure or temperature present during formation.

But I digress.

“Light Grenades” is neither that highly formed jewel of a perfect rock album, nor a lump of coal in our stockings this holiday season. It allows us to take a certain pleasure in being sad or lovelorn with the overtly cliché “Love Hurts,” while punishing us with ennui and vertigo with the dizzy “Quicksand.”

Then again, who knows what subtleties lurk in this appealing but generally unremarkable album? As Incubus reminds us in the two-part rock ballad “Earth to Bella,” which stands out as one of the better tracks: “There’s so much more to get, they’re wrong.” Maybe he’s right.