If someone overstayed in Canada and left, will their passport be?
Its not going to be blacklisted, but depending on how long the overstay was, the person may find themselves having difficulty securing future entry or visas to Canada and other countries that share immigration information with Canada (US, UK, Australia, New Zealand). He/she will be able to visit countries that allow them to visit, but if he/she tries to hide the overstay, that list of countries is going to shrink.