I always go onto the states Department of Fish and Wildlife and do a bit of searching. I find the answers most of the time. Some states offer permits I believe, but I know that a lot don't as well. For instance, the state I am in, Washington, has supposedly some of the worst regulations in the country, it's blacklist is gigantic. There are not very many species that are legal to keep that you can actually find in captivity. AND they don't offer ANY permits. I believe it is similar with Oregon and California.
But like Jennewt said, many people don't actually know the regulations of their state. And in my case I was very confused about the regulation until I emailed the Washington Department of Fish and Wildlife and got real answers as the regulation page was quite difficult to 'decipher' and was quite confusing.
I sort of have figured out how to find out if stuff is illegal or not through the mentions sites, and if I am going to sell anything I will make sure it is legal first. But there really isn't a very 'fast' way to find out, it might take an hour or two.
Anyway, I hope that answers your question. -Seth