Not necessary true, but the green tip is strong and bitter and should be removed anyway, if possible. Some people who eat a lot of garlic claim their digestive system adapts and the smell of garlic no longer lingers, but this is not proven. The theory that only raw garlic smells, not cooked garlic, is also folklore.
Scientists do agree, however, that garlic, a traditional folk remedy to 'cleanse the blood' of impurities, does have anti-clogging properties. They recommend eating it often for a healthy heart.
** Asian Online Recipes