Display gifts are simply those that serve no purpose other than to be looked at. These can be absolutely gorgeous and even cost a lot of money … but they also might not truly be appreciated or a wise choice.
If a gift needs to be displayed in order to be enjoyed, then it probably will require dusting (hence the name “dust collectors!”) Too many little knick-knacks can make dusting tedious and make the items less enjoyable. A cabinet with a glass front is a great place to house items like that where they can be enjoyed from a distance and protected from excessive dust collection.
So before you give a dog owner a “dust collector” gift, consider if they have somewhere to keep it free from the elements so it can be enjoyed without causing extra work to keep it clean. It might be a better idea to get some other kind of pet-themed gift!