THIS WEEK'S PIRANHA 3D isn't just a cheesy, gimmicky throwback to '80s glory. With a cast including former greats like Richard Dreyfuss, Ving Rhames, and Christopher Lloyd, Piranha 3D is standing (swimming?) in a big pile of sticky Hollywood trash—a pile that, like a black hole, sucks in once-great actors hungry for gigs.

Take one of Orson Welles' last roles, as Unicron in 1986's Transformers: The Movie. It's a testament to Welles' skill that he could deliver pure dreck and still make it sound good. Besides, he was doing frozen pea commercials before Hasbro came knocking: "Hey, fat man! Wanna play a planet in our toy commercial?" Orson understood a truth many actors struggle with: A check is a check.

David Carradine got it, too: He worked on 50-plus projects after the world rediscovered his sleazy brand of smooth in 2003's Kill Bill. All paled, however, in the shine of Dinocroc vs. Supergator (2010), released one year after he was found in a Bangkok closet. There's a bit of (bad) poetry to the fact his career basically began in Roger Corman movies, and ended there.

Normally, Corman catches talent on the way up—he helped foster James Cameron, Martin Scorsese, and John Sayles—but his gravitational pull yanked down Captain Kirk himself, William Shatner, who played a sweaty slab of man-beef in 1974's Big Bad Mama, causing nerds everywhere to wonder how the mighty captain of the Enterprise became a pinstriped man-whore toting a Tommy gun.

Almost as many wondered how the once-proud Raul Julia could have possibly agreed to slum it with Jean-Claude Van Damme in Street Fighter (1994). It wasn't the money, although the check was nice. It wasn't the character of M. Bison, although he ate the role up like it was delicious candy. No, it was because his kids asked him to.

Shortly thereafter, Raul Julia died. If that's not a good argument for contraception, I don't know what is.