If you're talking about the music from the Fecal Matter demo that made it onto Incesticide, only one song made it on: Downer. I'm a huge Nirvana fan, but a lot of the early material on Incesticide didn't do it for me. Only Hairspray Queen (the weirdest bassline/vocal melody pairing I've heard) and Sliver (which is dumb, but catchier than the flu) and a few others do it for me on the stuff recorded before 1990. I think it could've been better if they released songs like Sappy, Spank Thru, or Even in His Youth, all of which had been recorded at least once at that point.