He has a point here, if you are concern about the batch, you can identify by the serial no. However, I've no idea the exact way to identify so. You might wanna google it.
The reason why I believe he has a point here is that, you can have all the time you want to test the camera out before you buy. Do not submit to pressure from the shopkeeper. For anytime you feel discomfort with the camera, be it 1 hotpixel or even superstition (Oh my gawd, I feel as if something's coming out from my LCD screen, it gives me the creep
), then you've all the right to walk out and not to buy it. It's all down to a few factors, how confident you are in testing the camera and how courageous you are to reject the camera (and reject as a whole) if 1 or none of those camera you tested out is to your satisfactory
