I'm going to defend human nature a bit here because there always seem to be a bunch of posters who go on about MUP behavior being ***versally bad. Every once in a blue moon I encounter something like that described in the op, but for every one of those, I have hundreds of people who will thank me for announcing my pass. Once in a while, I even have to tell someone they don't need to apologize for walking or riding two abreast, I am just letting them know I'm there so they won't go to the left in front of me. Most people are either nice or just cooperative without any fuss. This is true on urban, suburban and rural paths I have been on.