The proverb simply means that appearance is often deceptive. A thing may be out-worldly attractive and tawdry. But on a deeper analysis it will be found to have no intrinsic worth. In fact, only a defective thing needs artificial make-up or superficial gloss. So one has to be careful and cautious in judging values. A bed material requires advertisement to push sale. A good wine needs no bush. The imposter impresses quickly. Similarly, a gaudily dressed man is not the eminently qualified man.