Depending on the make and model, send a reverse feed code and then overwrite with block characters. You will know that something bad happened, but you won't know what.
That makes it inconvenient to read, not impossible. E.g. use transmitted instead of reflected light (shine a bright light behind the paper) to see how much ink is in each place.
So overwrite with random patterns of dots. You could "arms race" this all the way to the point where you need a scanning electron microscope.
But this line of discussion is entirely missing my original point.