My blood is boiling, but my brain isn't IBM.

[DragonMasterX]

Well theres many reasons why they breathe fire...i personally think they eject all waste gasses orally, and flammable gasses are ejected in this group. These ignite due to the extreme temperatures built up in the dragon's throat.

There are many reasons, yet you missed the obvious one. The flammable gasses are located within their lungs, explains why they can eject both smoke and flames from their mouths and nostrils. Lungs are not directly connected to the blood-circulatory system; lungs manage Oxygen and Carbon Monoxide exchanges, not blood circulation, thus having warm or cold blood would never really mean a being could breathe fire or not. Dragons are supposed to have lungs filled with ignite rocks. (LOL KIDDING, but the the gasses still are in the lungs.)