Spitting Cobra's occasionally drop small amounts of gold. I believe this is not intentional.
That's from swallowing their pray whole. Hin sometimes have gold om their person. Snakes don't take the time to pick that out.
In fact, up the loot to include random other accoutrements that prey might have been carrying! ;)
Spitting Vipers still drop loot from the ordinary loot table. Coin, torches, lockpicks, herbalism tips.