Carpe Diem

Hello, I wonder if anyone had any advice on identifying whether coins have been polished by using only pictures? For example, if you're looking to buy coins online and want to spot signs that someone's gone hammer and tongs with the Brasso? Here are 3 examples I just took from eBay and would appreciate your thoughts on them. The 2nd image for example has smooth, lighter areas but then darker shading around the lettering - is this a clue? Many thanks