In Nautilus with Places siderbar you can use Backspace key to delete selected custom bookmark. This is very counterintuitive. Backspace is also used in the folder panel to travel to a folder up in the hierarchy. The thing is it is very hard to distinguish where the current focus is - in the folder panel or in the places sidebar? By using Backspace I am regularly deleting my bookmarks by mistake!

You can also use Delete to delete the bookmark. This is completely satisfactory because when pressing Delete the user is paying higher attention what exactly is he currently deleting. But not when using Backspace. Also it is not usual to delete any menu items with Backspace.

The Backspace key functionality should be removed from Places siderbar, because it is very user unfriendly and causes user data loss by mistake very often.