Answer:
Artists generally get upset if they find out their art has been used or reproduced without their permission. Whether the art appears in print, on TV, in video, film, on the Internet or in other artists' works of art, instances of using images of art without asking first are more prevalent than ever. While it's true that art used in unauthorized ways is usually an infringement on the artist's copyright, the question then becomes whether or not to do anything about it-- legal or otherwise-- and if so, what?
Treating every such incident as an actionable offense by going legal is not necessarily the best way to go. But many artists go right ahead anyway and attempt all kinds of actions regarding unauthorized use of their art. You can sometimes see the results of this in commercial stills or videos, for example, where art of any other kinds of identifying imagery are either blurred out or not shown at all.
Whether artists who make claims end up winning judgments isn't the point. The point is that defending against these claims takes time and money. For artists, the fallout from all this is anything but good. Those who are interested in having their work appear in any kind of media anywhere are having more difficulty than ever accomplishing this, whether they care about getting paid for it or not. Why? Because many companies are no longer willing to take any kind of risk and have simply sworn off picturing art in anything they do. So less art by fewer artists gets used. The ripple effect from all this is that the general public is exposed to less art in mainstream media and publications of any kind.
Keep in mind that many artists do receive payments or royalties for art that appears in major corporate media, but not always. Reasons for non-payment vary. Not all companies have the budgets to include art in whatever they produce, and many have barely any budgets at all. So the question any artist faced with a possible copyright infringement issue must ask is this: Are the "violators" using your art exclusively to make money for themselves or can the situation be looked at in other ways? In the above example, the art in question did not increase the show's revenues, but rather honored the artist and hopefully encouraged more people to buy art. The set designers could have just as easily hung a public domain print or a poster or even left the wall blank.
Another aspect of this issue is when the artists are asked to lend their art, but are also told there's no money in the budget to pay them. Blurring out brand names and images. Database of artists who are willing to allow their art to be used in TV, film, advertising, etc. If the production is bigger than you are, and they can do more for you than you can do for them, do whatever you can to be part of whatever they're producing. Don't look at them as moneybags. Many of them have hardly anything to doing this on a shoestring. If it's a corporation using you to brand their merchandise or attract followers that's a different story. But if someone in the production company happens to love your art, allow them to express that love freely and pay homage to you in their production. Is the art being used to make money for the production, or is it being used because set decorators really like the way it looks? They can find all kinds of art, but they chose yours.