[Pxtl]

That does restrain them a bit though - with a watermark, they can batch-change the nature or obtrusiveness of the watermark, they can resell the unmarked images, they can update their logo freely.

None of that can be done with the real-world-logo appearing on the product.

[sentenza]

It might be possible to use a greenscreen, though.

You do your photoshoot with a greenscreen in the background/part of the background, then digitally replace the grenscreen with your logo. Since your logo and the product are mixed at the edge pixels, it will look crappy if cropped, whereas you yourself have the greenscreen originals and can change the background whenever and however you like.

[Pxtl]

If you wanted to be really super-fancy you could apply some image recognition decals to the greenscreen that would allow a program to determine the orientation of the platform below or background behind the object. Then you can actually do a more sophisticated projection of your logo onto the surface and keep the shadows provided by your subject. But at this point it's gotten a little sophisticated for a small seller.