I think I can pretty much confirm they DO NOT drop in Altar, Bloody Swamp, War Torn Plans, and EV. I've killed a TON of mobs in these three areas on alts and nothing.
I've gotten about 50 on my main on Alligator Island. I've gotten about 120 Coins, 2x Zodiac Cube Frags, small amount of adena and, just this morning, Leviathan Gaiters!