I 100% agree with the above comment, when I am out walking my dog, and I come across someone else walking theirs, I go out of my way to avoid a meeting. I will shorten up my leash and cross the street or trail. I tell my dog "on by", and he knows that means, ' pay that dog or person no attention.'
I too have heard of the yellow ribbon indicating ' no approach'. I try to live by that motto when out walking.
When I want to socialize my dog with others, I take him to a fenced dog park. Most dogs are in much more ready for social time off leash in neutral territory. I find however,that I do this less and less when traveling. We have our regular group at our home dog park where it is much more stress free!