1. California is not dominated by incorporated city limits and prohibited areas, and therefore (geographically speaking) most of the state is loaded open carry territory.
2. Large numbers of metropolitan police do not respect armed citizenry, but many have shown that they are educating their officers. There may be individual officers who will take it upon themselves to discourage OC as well.
3. Open Carry is not as accepted in the metropolitan areas. In spite of this, OC isnt a guarantee of a 911 call or does it ensure that there will be a police encounter. Most people mind their own damn business like they ought to.
See CaliforniaOpenCarry.org for more information.