Here's a scam I hadn't seen before. Fortunately I asked my attorney about it first.
I recently registered a trademark, and today I got a bill in the mail for the registration, apparently. It was quite vague, but seemed like it came from the European branch of trademark registration.
The situation is that since all new trademarks are on public record, some unscrupulous companies make up official looking bills and send them to the owners of the trademarks. In my case, though it was far from clear, what I would be actually paying for was nothing official, but just a high fee for a listing in some book they print which nobody uses. Sort of like these poetry contests which makes you pay handsomely to have your poem printed in a volume of "winners", and then buy the book, at a very inflated price. And of course nobody but the victims actually buys the books, to see their name in print, so the supposed prestige is nonexistent.