If a user hasn't copied anything, would it be a good idea to disable the "Paste" menu entry and replace the text with "Nothing to Paste" instead of just disabling it?
Menus aren't always static, often "Undo" has some text added to explain what will be undone ("Undo Remove Folder" for example). Other examples of dynamic text I have seen is "Copy 4 items" if 4 items are selected, instead of just "Copy".
Since it's a OS controlled menu, I can't do anything with hover effects to modally give the user an idea of why "Paste" is disabled.