This may be old, but the random feedback this guy left is pretty funny and a great time waster: Linker
Actually, I don't know if it's still this way, but at one point you could leave feedback through a URL - that is, if you clicked on a feedback URL for a legit person, you could plug another username and a valid item number into the URL in the browser bar, and leave feedback. They may have plugged that rather obvious security hole, though.
Hey stinkyboy, what's your e-bay username? neaky: Hah! Like I want all of you to see the perverted things I am buying on e-bay. Mines actually pretty obvious.