I doubt the signals are random. You should see a cascade of values. So if the port you have a sensor on shows X, then you will have Y on the next port where Y < X. The next port will have Z where Z < Y < X and so on. Floating nodes pick up the last sequenced channel. As soon as you connect a sensor, it goes away. So basically once you use the port it works as intended. If you just watch it there, it will do funny things. You can do the same thing by grabbing the two end pins on a channel and squeezing.
LEDs are only for the outputs. Inputs have no LED status.