Because a large over-population of vain artists flock to galleries offering to consign paintings at essentially no cost to the gallery, the art business sometimes amounts to little more than theft. I do not maintain that all galleries are shady or dishonest, but most artists have had some bad experiences with galleries at one time or other. Many are so happy to have their work accepted that they fail to get proper receipts. If any works sell, the gallery can just keep the proceeds of the sale. Artists frequently have to sue galleries and more than a few gallery owners have been known to vanish with the proceeds.
Now and again we see newspaper articles about such scandals. I have known artists who have had no end of troubles leading to lengthy costly lawsuits against dealers. I have also known of dealers who spent most of their time avoiding telephone calls from irate artists and dodging summons servers.
The root of this trouble often lies with the artists because so many of them prefer to live in a kind of ethereal dreamland and steadfastly refuse to learn anything about the business aspect of their profession. Many are ripe to be fleeced by unscrupulous dealers.