I grew up hearing that Komodo's were not poisonous, but that their mouths were infested with abnormally high amounts of especially nasty bacteria. Supposedly when they bit something, it would take 2 to 4 days for the thing to die. The "dragon" would stalk its dying prey until it finally expired.
However, the recently finished a DNA analysis of the Komodo's (and other lizards, to include iguanas) and determined that the Komodo is actually more closely related genetically to a particular kind of poisonous snake than it is to other lizards. So they looked again - to discover they actually DO secret poison. They also determined that iguana's were related to a kind of poisonous snake. This cleared up a minor mystery. It was supposedly well known among those who like exotic pets that iguana bites were often a lot nastier than one might expect from the size of the creature inflicting the damage. It was assumed that they, too, just had germy saliva.
