Some looked pretty real, but some just seem to be given away by the lighting on them that they're not real such as the knife, it's too white and stainless for a reflective material. Or that truck, too unnatural color. The car's back has a white reflection that might give it away. Cones are too reflective and the egg decoration's golden flowers seemed a bit too strange for a real material.

The pool seemed the most realistic of them all, followed by the room with sofas but that TV again seems strange.

They also might just think it's an icon for what is on sale (not sure if websites of markets would put CGI objects to represent what they really are selling or they use the real thing, seeing as most of the products are over a white background).

What would be interesting: a test to see if humans can tell the difference between real pictures and CGI.