There is a kind of artwork, often the best, that is very difficult to market, due to the subject matter.
The particular "kind" of artwork I am thinking of is the art created from those in stress -- the mentally disturbed, the mentally disabled, the family member who has lost someone due to a mass shooting, first responders, soldiers with PTSD, an abused wife or child....the artwork comes from people who do not normally consider themselves as artists, but they are....
1. Monitor agencies that support people -- not just artists -- under duress, and ask if they would consider hanging the artwork with difficult themes in official offices.
Already, one example I'm thinking of, is at the United Nations.
2. "Market" (I really hate to use that word) the story, not the artwork itself.
There is sometimes a merciful disconnect between the story and the artwork. One can read the horrible stories of child abuse, but it is harder to look at the artwork of a child who has been abused. So, provide a more genteel path for people to understand the story of the art. When they're ready, they'll view the art.
3. Start by putting the difficult artwork in display in locales that have a history dealing with the difficult -- or historical --subject matter.
If, for example, there is an office that deals with abused children, the workers are familiar with the unfortunate stories behind the artwork -- and should be encouraged, WITH THE APPROVAL OF THE ARTIST -- to hang the artwork of these people in the office.
If handled correctly, this can actually be part of the healing process for the artist.
Then, get a way to fund the room that hangs the artwork -- it may need to be somewhere set aside -- with at least part of the proceeds going to the artist.