I guess I don't have as much faith in their skills in cosmetics as you do.

After all, this is a race of people where in some parts, they keep their women fully clothed and behind veils, so... \:p

[/joking]

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This is why greater security is needed, particularly with documentation. You could turn Mohammed Atta into Mrs. Doubtfire, but if there are improved checks, it would yield nothing.

Plus, costumes only make it harder for them to carry bombs, etc.