Kalena,
The quote "Laurel and Hardy of the Surf Crowd" comes directly from the liner notes on their Command Performance album from 1965.
In 1971, Dave Marsh wrote: "The liner notes here [Command Performance ] call them 'The Laurel and Hardy of the Surf Crowd,' a misnomer in several areas. They were about as much a part of surfing, by that time, as Frank Zappa is of the classical music continuum. Hell, Jan & Dean were the Clown Princes of rock and roll and to avoid the fact by generically limiting them to surfing and hot-rodding music is simply ludicrous."
It comes from their whole experience . . . the music, public persona, and video evidence.