Here's how it works:

Someone contacts you and says they are interested in a puppy. They may say that they are contacting you directly, or that they are an agent of another person. Either way, they are typically outside the US. Furthermore, in the emails I have seen, they seem to refer to the puppy in an odd way, such as my employer is interested in "PUPPY" that you have for sale. Obviously, this is your first big red flag.

The email then states that the author or their "employer" would like to send you a bank cashier's check, or certified check, that is significantly in excess of the amount you are asking for a puppy. They want you to pay them back the difference in cash. I've seen several explanations for this... my employer has pre-authorized this check amount, or the remainder is for shipping, so please pay that amount to my shipper when he picks up the "PUPPY."

At any rate, the bank cashier's check that these scammers send is counterfeit, but it is such a good counterfeit that you can probably cash it at your bank. Only after you have paid the "difference" to the scammer, either in person or by wire transfer, does your bank find out that the check is counterfiet. At that point, your bank will hold you responsible for the total amount of the check. In some cases, someone has actually arrived and picked up the puppy, and of course who knows what fate the poor puppy meets. In most cases, though, all the transactions are handled via wire or mail, and at the very least, no one ever shows up to get the puppy.

This is a terrible scam, but it should point out a few things...

1- If you are extremely careful where your puppies go, find out everything possible about the home they are headed to, and really get to know the person or family, then you'll never have to worry about this scam at all.

2- There was a time when a bank cashier's check or a money order could be trusted. Not any more... counterfeiters are slick.

3- If something sounds fishy, IT IS.