I don't see any problem with it, and I'm curious why you would. It's a replacement for a used phone. The replacement phone is going to look and feel brand new. It will have been tested over and above a new phone. And it will be warranted the same as a new phone.
When the Apple haters discuss Apple suing Samsung for copying the iPhone design, design doesn't matter. When Apple releases a new phone without any design changes, design suddenly matters most. Hypocrites.