Bicycles can be as dangerous to pedestrians as cars are to us. Sidewalks are for pedestrian traffic and tricycles. Bike trails are shared access for pedestrians and bicycles. Roads are for shared access for cars and bicycles. Simply rules. If you want to be respected on the roads, respect users of the sidewalks as well as the roads.
If a sidewalk needs to be redesignated as a bike path for safety reasons petition to get it changed or buy a car of paint to warn pedestrians that thatsection is shared use.
If anyone wants to complain about "defacing" public property, I suggest that it is simply a "non-violent" social protest against the non-responsive local government. I guarantee that most pedestrians will appreciate the warning rather that having a cyclist blast past unexpectedly.