Plant secretion termed 'honeydew', usually a sign of good health in orchids. I've seen it on leaves on some orchids and on buds on others. I like to spray my plants with water thoroughly to remove it to prevent fungal infection. Shaun
You should also check to make sure that there are no bugs on the plant - either brown spots(scale), or white(mealy bugs), or aphids. As bugs will be drawn to the honeydew.
