It seems to me that the reptilian folk of D&D don't have a lot to differentiate them. Consider the poorly named troglodyte: It's only distinguishing factor from a variety of reptile-men is that it lives underground, and--well, stinks.
Alright, maybe that's a little unfair. Still, at the end of the day, the troglodyte isn't on anybody's "best monster list."
But what if the troglodyte looked less like a chubby lizard-man and more like this:
Now that look opens up a whole new set of associations...
"Sinuous bodies that moved with effortless ease, seeming to flow rather than step. Hands with supple jointless fingers and feet that made no sound and lipless mouths that seemed to always open on silent laughter, infinitely cruel. And all through that vast place whispered a dry harsh rustling, the light friction of skin that had lost its primary scales but not its serpentine roughness."For one thing, the Sleestak image reminds me of paleontologist Dale Russell's hypothetical Troodon-descended, dinosauroid sapient, to whom the Sleestaks bear an uncanny resemblance. For another, anyone steeped in Land of the Lost lore knows that the Sleestaks are the degenerate descendants of a once advanced reptoid civilization.
- Leigh Brackett, The Sword of Rhiannon (1949)
Maybe troglodytes are a similarly fallen race, and maybe, like the dinosauroid, they share an ancient lineage. Maybe they were once the rulers of the world, before the rise of mammals. Whether this civilization was more like that of Robert E. Howard's Serpent-Folk or Harry Harrison's Yilané, is a matter of taste. Maybe it was a bit of both. Note that the world they were the rulers of need not be the campaign world--planar travel exists. In any case, they ruled from a lost continent, an ancient Mu or Lemuria, what have you, until some cataclysm (the arrival of the moon, perhaps? Hey, it go Doctor Who's Silurians out of the way) drove them underground.
Or maybe, it drove them all the way to the Hollow Earth. If so, maybe an advanced reptoid civilization still thrives there, waiting for the chance to try to regain the surface world. Or maybe they changed with the eons, too. A review of Burroughs' Mahars of Pellucidar might be instructive. Even in this rosier (maybe) scenario, some of their race wound up in-between the inner and outer worlds, in caves, slowly devolving and losing their ancient grandeur--becoming primitive and brutish, and possibly anthrophagous. In short, they became troglodytes.
So, its pretty easy to see where one might go with this. Like with the Sleestaks, there maybe be atavistic troglodytes who have intelligence (or even psionic powers!) not possessed by their peers, for adventurers to encounter. And of course, there could be an army of magical biotechnology armed reptoids waiting for the chance to bust out of the inner earth and lay low upstart mammalian civilization.
Maybe that disgusting stench is smell of troglodyte victory.