Los Angeles is well-versed in deception. Bring water to the desert, and everything will turn green. Build miles of freeway, and no place will be out of reach. Promise a dream, and the city will grow.

Though it has been seen by thousands of people since its installation in late January, the new “Welcome to La Jolla California” sign at Torrey Pines Road and La Jolla Shores Drive got a ceremonial ...