The trip we took with Rodbender Charters they were not allowed to take anything across the border except clean night crawlers. No dirt, etc. as been said. Just rinsed off in water and in a bucket (I believe). As for other stuff (Shiners, soft craws, etc.) you had to go ashore (which meant a trip into customs) to get them. Just a pain in the rear if you ask me.
Went to Canada two weeks ago with a cooler that had a flat of nightcrawlers that we had ordered ahead of time. They were actually ordered from a Canadian company and came packed in regular soil. We were radomly inspected at the border and I watched the customs agent open the cooler they where in, dig a bit, and close it up. I thought for sure I was busted. But they handed me the keys, apologized for the delay and sent us along. Couldn't have been any friendlier. Mostly just checked the inside of our prescription drug bottles. Hope that helps.