The foam backing imprinting the back of the phone. I agree, nothingburger. Anyone that says otherwise needs to learn how to clean their phones.
As for the difficulty of removing the case. Yes, I agree that it can be difficult, however, most people that go for a Rugged Case are not prone to removing the phones.
Trick to getting your phone out of this case is to start in the Lower Right corner of the case. You will see a slight inner bevel there and that makes getting it loose initially easier than anywhere else. Once you have that separated from the top frame, just run your finger up the right side to "break away" the outer case from the inner frame and it just comes out.
Hope that helps!