Fake signatures are an unfortunate aspect of TTM. There are a few types of fake signatures...
These are signatures written by a person, but not by the person it is supposed to be. These are usually done by family members, secretaries or other hired assistants. Hockey player Mike Modano has been rumored for years to have his mail requests signed by his mother.
These can be difficult to detect since they are real signatures. Comparing to authenticated signatures of the real person can be one way of determining if what you got back is real.
|Image from stamp-connection.com|
|Image from theblaze.com|
Ok, TM is not perfect. And nothing can insure that you will never get one of these fake signatures, but by doing your research about who you are wanting to send to and keeping up on the news in the TTM community, you can guard against it and enjoy the hobby.
Here is an article from Autograph Magazine that goes into more detail.
May your mailbox be filled with autographs and not bills!