[Cash]

I used to live in the Bay Area, for 10 years... I didn't have a Rottweiler at the time but I frequent my friends who still live there. I have brought Cash to Baker Beach, the parks down at Crissy Field, Union Street shops, Fillmore Street shops, and all of the "snotty" areas you can imagine. I am full aware of the issues with our breed, and I am actively now fighting BSL down here in LA.
Nothing, I mean NOTHING, dispells the myth of a vicious 'breed' than the public meeting a great ambassador. I frequent a stretch of beach down at Seacliff with my dog on our visits. We practice a few OB lessons and then we would walk the beach. We met very nice people on our outings and had many a discussion as to why Rottweilers get a bad rap. But, I know in my heart that if they didn't see a well behaved dog they never would of approached us. Take pride in your dog and stop punishing him for something he has not done. There is no need for your dog to wear a muzzle. You cannot change the minds of people that cross the street because they don't know your dog is friendly. Worry about affecting the people that are wiling to engage you, and respect the fears of the others. You most likely won't reach them anyway. Unless and until your dog 'needs' to be muzzled it's supremely unfair to him to have to suffer a public paranoia.

I don't know who your trainer is - but I would dump him/her. Immediately. If you need a reference for a good trainer just ask. We have a lot of members in your area. :)