While that may be true, you haven't quite got the life-choice correct if you are just hiding your opinions. My original post was intended to say that everyone should both be treated with respect and genuinely have it as well. Until they lose your respect.
Now if you take one look at a person and see reasons for them to lose your respect, that's ok. What we show to the world does indeed change their opinion of us, and should be included as a factor that influences how other folks think of us. Life is like a job application: first impressions do matter.
I'm also a firm believer that it is wiser to keep my low opinions of other folks to myself. It's not usually beneficial to me to go around pokin' at folks for no good reason, and showing respect of others is definitely part of projecting to the world who I am.
Zin doesn't seem to think that is important, either.