In France, they starve snails for about 3 days so the insides are clean,
and then boil and prepare them (forgot the details, but it is a long
process, like many French recipes), followed by cooking in garlic butter.
It is delicious! I don't know if any snails are dangerous as far as
toxins, etc., that could be one thing to check before serving!
At one festival, they didn't starve the snails and it was obvious. The
pot of snails looked pretty green and slimy, and my French friend and I
didn't eat that batch!