lol, my best friend (79 countries) and I (73 countries) are doing a contest to try and visit the most countries in the world.
We always argue what counts or what not and try to bend the rules in our benefit. If landing somewhere but staying on board the plane doesn't count, I have to scrap Azarbaijan but he has to scrap Iceland and the Ivory Coast from his list. If changing planes but staying within the airport territory, I have to scrap Russia and India, but he has to erase Libya. If you have to spend at least 24 hours or overnight, he has to erase Argentina, Paraguay and Birma as well and we will both loose Macau.
So we wish there would be a definitive answer on this question