Just want to add that there are rules for vendors when posting there promo images, not sure if thats what the OP is referring to, but vendors cant simply advertise there products as they want.

But personally i would prefer to see products in a basic setup, and if it looks good or just decent there, you know as user that if you spend some time setting up a decent scene with nice lighting etc, the product will most likely also follow along. As you dont really know how long time have been spend on a "super" render, and then you might be very disappointed when you actually try the product and cant even come close to getting the same result.