L.G.
I had a german shepherd ( with a purple tongue/ half Chow ) , he looked VERY intimidating. This was many many moons ago but I still to this day remember one of the ladies who lived in my apartment complex. She was terrified of my dog- Ozzy. I used to take him everywhere I went ;).
I couldn't figure why in the world she would be so scared, he was one big bundle of fur and fun. If she saw me and Ozzy out in the parking lot, she would not step out. One morning I was out front messing around with my flowers ( dog with me ) she was late for work because she would not go outside to get in the car.
One day she approched me and told me terrified she was of my dog, I offered to let her meet him so she could see he was harmless, she said 'no way' and I didn't push her on it nor did I discount her fears. From that point on if I saw her out and I had Ozzy with me, I waited until she was inside before I let him out of the car or I would take him for walks on a different path so as to not go anywhere near her apartment.
My thing is, just talk to the dog owner. Hopefully he/she will be receptive. I don't think there are bad dogs, just bad dog owners.