I wouldn’t keep them unless they actually support your mission. I just came back from a wonderful workshop, hosted by the Dakota Territory Museum in Yankton, where this topic was brought up.
The DTM director has a policy and procedure manual that explicitly states their mission. No donations are taken unless they support the mission, the board is told when items are donated as well as why things are or aren’t taken. It’s all very transparent and it keeps the community from using the museum as a dumping ground.
Contact Crystal Nelson – 605-665-3898 for more information. She offered to make her manual available to those museums in the process of writing their own.