Some of the trades are really nice, but I've heard that you can only do a trade once, and I don't want to lose my items if that's true.
41 Answer
Just make sure you don't drop the entire stack of items, and drop them one at a time.
if you drop them all in one go, they'll be used up as one item iirc.
As per the commenters, after dropping one item, and receiving one from Snuggly, you need to reload the area either by leaving, or saving and reloading to continue to trade.
4