I don't see how anyone could be thrown out for cheating with a provided-boat event (at least, not for illegal masts, extra-wide boats, etc.). Totally losing me here.
2007 Pan Am Games in Brazil. Home team had some questionably class legal mods to their boat (old style mast head on Comptip, corner castings moved out on crossbars and re-riveted to increase beam). Talk to Bob M. - he was there and filed the protest that eventually had the Brazilians tossed out - they would have won the event. Boos and trash thrown at competitors and officials at the prize-giving ceremony.
It's the reason we have the "maximum sail hoist diagrams" in the Hobie Class Rules now.