A man dances with a woman in a white egyptian costume.
A man is disguise as he dances with someone.
The woman wearing a costume does not imply the man is also in disguise.
It is not necessary he disguise to dance
A man may dance with a disguise or a man may dance without a disquise; since there are two possibilites, it is not certain that a man is in disguise as he dances with someone.