I had a guest book a single night and asked to receive a letter at my address. He said he was attending a conference and they would be sending a confirmation code for his attendance here in NYC. He had two positive reviews and I thought it sounded legit. I've also been hosting for four years and never had a problem so I agreed.
He called the day before he was to arrive and said he wouldn't be coming because the conference was cancelled but that he needed the verification code so he could sign up for the next one. I told him the letter arrived. I noticed it wasn't addressed to a person but a business, WILLIAMSBURG IRON PRODUCTS at my Williamsburg address and was from Google Business. Luckily, I'd run a web development company for two decades and this looked familiar.
I opened it and it was a verification code but didn't mention any conference. It said along the lines of, "Enter this verification code into google businesses and start letting customers know you're open for business." I knew this flyer. It was how Google Places verifies businesses are at a physical address. The guest insisted it was in relation to his conference. I called Google Business, sat on hold a half an hour then spoke to a manager and he verified I was right.
The only purpose of the letter is to verify a physical address and had I sent that code to him he could have removed my existing business (Graphic Designer) from that address and put this ficticious one there in its place. He said destroy the code immediately. And I did.
Be warned fellow hosts!!