Actually I think we do know in many if not most cases that matter.

Most for profit galleries have nice lighting.

Most people who are going to spend a significant chunk of change on a photo will be open to suggestions from the gallery or you.

If the work is a commission you will know the target.

As to public showing spaces or others with poor lighting, you do have the choice not to display your work there. Seriously, do these spaces even fit your market? If they matter and it's going to be long term maybe a print needs to be made specifically for that space.

The flip-side thought there is that I think most people understand bad light, if the content is strong much may be forgiven in public that can be fixed in private.