Here's another example similar to the heat thing: the idea of disesase.
Dany isn't afraid of the bloody flux because Viserys tells her that Targaryens don't get sick. He's clearly exaggerating as we've seen Targaryens die of disease throughout history. However, this is thinking in opposite extremes. It doesn't have to be "immune to all disease" or "normal". There is room in-between. It could be that they have better immune systems than most.
Just like the fire thing. Some people say "Targs are immune to fire" and some say "no, they are completely normal, Dany's thing was a miracle". Again, there could be room in-between. They could have a higher tolerance for heat, or even something like a higher normal body temperature. Dragons do give off a lot of heat as you say, so this fits nicely. Dany notices her dragons steaming while just sitting there as babies, for example. Riding a creature that hot might require greater tolerance.
Statistics: Posted by Azizal — Sat Feb 14, 2015 11:31 am