No, you should make sure that the place you are parking does not have signs limiting parking.
Many city and residential streets in the Los Angeles area limit parking to certain hours, days, or in a few cases to residents of the neighborhood. Private parking lots often limit their use to customers, employees, or specific hours or amounts of time.
That being said many (but not all) Walmart stores allow overnight RV parking (where not forbidden by local ordinance). Some larger shopping centers don't object to RV users parking overnight in remote corners. Most major truckstops have no problem with overnight RV parking, and in fact if you go into the rear area (which usually says "truckers only") they have a variety of laundry facitities, pay showers, and TV lounges.
Finally, most places in LA have a "72 hour rule" that allows a vehicle otherwise legally parked on public streets to be cited if it is not moved for 72 hours. While not usually rigorously enforced for smaller cars or trucks....RVs and commercial trucks are often targeted by parking enforcement, or called-in by neighbors.