It is also unethical to allow museum employees to purchase deacessioned items unless they purchase them at an auction setting, and even then it an be iffy. This prevents the deaccessioning of items specifically so that an employee can own it.

The criteria you mention are very common. In college I worked at the campus art museum and we also deaccessioned objects that were not up to museum standard. We had recieved hundreds of items from a gentlemen who gave us some high quality pieces, but the majority of the items were tourist quality pieces that had been independently appraised for a lot more money than they were actually worth, We finally went through all the boxes and chose about 50 percent to deaccession. Believe me, we had neither the room nor the need for this stuff. The money made from the auction went back into the collections budget, enabling us to fill gaps in our collection.