This GameDaily article on "Mascots Gone Wild" exposes some of the horrible things done by Nintendo's flagship characters (and friends) back when they were young, and needed the money. We're all quite familiar with the CD-I Zelda games, of course, but we haven't talked so much about the similarly abysmal Hotel Mario, also for the CD-I. "There's no jumping, no shell squashing, no recognizable Mario gameplay whatsoever – just opening doors and going through corridors."
Mario's other miscellaneous fringe material -- when he taught typing, was missing, and presided over a gallery of board games -- dominates the list, with appearances from other marred Nintendo characters, including Donkey Kong. Amusingly, Conker makes the list for his Game Boy Color game Conker's Pocket Tales, which failed to be filthy.