Sincerity is important in business, and being "furtive like a gui" or "deceitful like a gui" will only hold you back. As they say: "the wails of man and gui are quite different," so that we can distinguish between good people and bad.
做生意講誠意，「鬼鬼祟祟」或是遇到「內神通外鬼」自己扯人後腿，畢竟「鬼跟人號（哭）勿同聲」好人壞人要認清。