When the picture above was posted on Facebook, I giggled. Then I looked again, and realised that the point of the joke was that we so often judge by appearances. The colourful bird on the left may be a serious intellectual, and the sober-looking one on the right may be a happy-go-lucky free spirit. You can't tell by just looking.
The problem with labels is their partiality. They are 'partial' in two ways: firstly, they only describe one aspect of each complex human being, and secondly, they are partial in the sense of being biassed - they put people into categories, and divide the world into Us and Them, which is always a bad thing.
It is natural to try to make sense of our world by putting things and people into groups, and to use adjectives to describe these groups. But it can be both deceptive and damaging to do so. When we label people, we are making a value judgement about them, and lumping them together with others who may only share one characteristic with them.
Once again, the Quakers have it right when they write in Advices and Queries: "Respect the wide diversity among us in our lives and relationships. Refrain from making prejudiced judgements about the life journeys of others. Do you foster the spirit of mutual understanding and forgiveness which our discipleship asks of us? Remember that each one of us is unique, precious, a child of God." (italics mine)
Or as the Charter for Compassion has it: "The principle of compassion lies at the heart of all religious, ethical and spiritual traditions, calling us always to treat all others as we wish to be treated ourselves. ... And to honour the inviolable sanctity of every single human being, treating everybody, without exception, with absolute justice, equity and respect." Which means treating everyone as individuals, and not assigning labels.