Adam Shankman’s “Rock of Ages” keeps the streak alive: No good movie since “Aladdin” has relied for laughs on reaction shots from a monkey. Shankman has assembled a kitchen-sink cast for his affectionate homage to 80s hair metal, of whom approximately one (Mary J. Blige) can actually sing. The rest vary from barely passable (Catherine Zeta-Jones as the mayor’s wife, who’s intent on shutting down Sunset Strip, Tom Cruise as debauched rock god Stacee Jaxx) to unspeakable (Alec Baldwin as the proprietor of the Bourbon Room, Russell Brand as his lieutenant, Paul Giamatti as Jaxx’s venal agent).
