有趣的問題

女兒問：『壞人有沒有屋住？』
我回答說：『聰明的壞人，住的屋當然又大又靚；愚惷的壞人都有屋住——監獄。』但何謂『壞人』？倒要反問她。當然最有智慧的壞人，是沒有人能知他們是壞人。
My daughter asked, "do bad guys have dwellings to live?"
I replied, "well, yes, smart bad guys live in castle; stupid bad guys live in prison." But what is the meaning of "bad guys"? I need to seek her answer. I believe wise bad guys will never let you know "they are really bad".