I know what you mean. Last week, I tried to look up a place on eBay called "PMI Digital" (they're selling the 5D Mark III for $3,200). Their page said they were an authorized dealer, but I couldn't find them on the list. I finally figured out that their "brick & mortar" establishment is called "Profeel Marketing, Inc." (Profeel?!?), which is listed.
In the end, I decided not to use them. I called their sales line and immediately got put on hold (waited a minuted before hanging up) and then their customer service line, which was automated (you had to leave a message and then get called back - UGH). I went with J&R and spent another $44, but still a good deal!
PMI / Profeel sells on ebay for low prices. They aren't much for customer service, but they are a authorized dealer, and many buy from them. I've even bought a lens from them.
Undoubtedly, there are some inactive dealers on the list, and many times, the parent company name and the DBA name are totally unrelated, so its not easy to tell.
I'd worry more about companies that are not on the list than ones that are, and are inactive, temporarily or otherwise. You can always ask a company if they are authorized and under what name. If they do not reply, or put you on hold, its their loss not yours.
After all, Canon may send a letter to the inactive ones annually and ask them if they want to remain on the list. If they reply yes, someone is reading the mail at least.