From the introduction:
Your dungeon is too clean. Maybe it’s not your fault. After all, those gnomes on the second level are pretty OCD. They must spend several hours per day picking parasites off the hides of their pet bugbears and giant rat‐steeds. And then there’s that gelatinous cube on level four—sliding its bulk through the corridors and dissolving every little tidbit of septic Filth in its path. But despite the efforts of your clean‐freak gnomes and acidic jellos, the general state of the average dungeon should be just... appalling. I mean, can you imagine how obscene the stench rolling off your run‐of‐the‐mill lizard‐man must be? Something like a wet bag of poo collected from a Newfoundland who ate too much leftover Indian food. Yes. That bad. You can’t tell me that one of those guys isn’t ground‐zero for some sort of unspeakable crotch‐malady.
It just seems that—Gygaxo-naturally speaking, of course—the environment of the dungeon and especially the creatures within it would be carrying all sorts of creeping crud. Disfiguring diseases, skin conditions, noxious butt parasites, eye‐warts, etc., etc. Sure, there’s rot grubs—one of my Top 5 favorite classic monsters, by the way—but they’re just the tip of the old iceberg. Or they should be anyway.
Includes the excellent "D20/D30 Table of Dungeon-Funk".