If I had a dollar for every time I’ve visited a forum and seen a photographer urging their viewers to view the image against a dark background because it looks better, I’d be a millionaire by now.
Black or dark backgrounds naturally enhance any and all colours, they can even make sub-standard images appear really good but ask yourself this …. are your walls at home painted black or charcoal grey?
I can guarantee that 99.9% of people will answer NO to that and I can also guarantee that 99.9% of your customers who you try and sell images and prints to also do not have dark black or grey walls in their houses.
If you truly want to visualise how an image will look in your house then view it on an appropriate background colour such as white or off-white shades or other neutral tones. As a photographer you should also think a little bit more about this and stop urging people to view it on a dark background, concentrate on making your images look good on lighter backgrounds, that is after all the conditions that 99% of your customers will use to display your print.