I'm currently reading yet another story that has dragons in it. These dragons appear to be the traditional european variants with big wings (most Chinese dragons don't have wings). As the dragons are rather large and have tough scales and talons not to mention a big mouth full of very large teeth they are going to be a bit on the heavy side. in fact they are going to be very heavy indeed.
The thing is I have held Eagle Owls who are quite large but very, very light. Their bones and feathers are built for lightness as light things generally fly better than heavy things. They also need very large muscles to drive the wings. None of this is ever evident with dragons. Everyone seems to except that you can get a 5 ton lizard with bullet proof armoured scales flying by sticking a pair of wings on the side of it. It's complete and utter nonsense. You might as well make them exceptionally intelligent too.
I'm not a fan of dragons.