3.5 - A DUNGEON, with a DRAGON in it.

[hamishspence]

True- the "generally metallic dragons" comment applied purely to "dragons that can naturally turn into animals, rather than requiring spells".

Shadow and Deep dragons tend to be found quite deep underground though. I think Deep dragons are actually vulnerable to sunlight- which does damage to them. So finding them in a shallow woodland cave, or roaming the woodlands at night, would be pretty unusual.

[Morph Bark]

Dragons as Cats? Yes. I approve all over the place.

It explains why cats can kill commoners so easily.

[Malbordeus]

shadow dragons are pretty small for their age/cr. but something about a breath weapon that deals negative levels might be responsible. also the total concealment in shadow thing (hey look, i'm invisible and breathing on you!)

other funny dragons involve Red (facepalms, these are excessive), gemstone dragons, and some o the planar/elemental ones. (pyroclastic is silly), sand dragons I have a lot of time for (sandstorm).
problem with a dragon in a dungeon is - even if he was teleported in by a malicious wizard, the dragon can get out by breathing on/eating the walls to form escape routes. (sand dragons are usually found in desert environs, but they have brrow... so natural dungeon crazies. especially if said dungeon is deep enough that they can hide their horde with little in the way of interfearance. also... Physical Damage Breath Weapon!!! eat that resist elephants!)