This Term of the Week comes from a longer article, Tips for Avoiding Ghosting, by Aaron Montgomery.
Ghosting mainly occurs in sublimation when the ink is still active, even after you have opened the heat press. When opening the heat press, the substrate and paper might move, resulting in an image slightly skewed from where it was intended to be pressed. This will leave a ghost-like image and ruin the blank. Unfortunately, there is no going back from this, and you have to start over.
Ghosting can also occur in screen printing—find out more here.