Smugglers

My friends and I have been playing with the smuggler for the past couple days... The first notice about the smuggler spawn appears at 7PM in-game, he spawns at 10PM, and he disappears at 6AM. Your town credit loss is equal to 2x the profit you make selling to him, and the today's item is stated in the scrolling notice that gives you his spawn location. Only the first trade with the today's item gives no credit loss, and it's once per real-time day, so even if you trade him the today's item on a different in-game night, you still lose credit if it's the same real day.

Also, either he doesn't spawn every night, or not every merchant player gets the scrolling notice every time, because some days I got nothing.