Yeah, well, for starters, I mean, you would probably need an elderly victim whose eyesight was shot so much to the point where he wouldn't notice the switches.
أجل، حسناً، كبداية، ستحتاج لضحيّة مُسنّ، حيث بصره ضعيف ولن يُلاحظ الإستبدال.