If you've got a piece of autographed Rolling Stones memorabilia ... that you didn't see them sign personally ... there's a chance it's FAKE. But that doesn't mean it was NOT signed by a member of the Stones.
Former bassist Bill Wymansays, quote, "There were stacks and stacks of autographed books, programs to be signed, and we just used to grab a bunch each and sign everybody's name.
"We all learned to sign each other's signatures, except for Charlie [watts]. he wouldn't sign anything. but me, Keith [Richards], Mick [Jagger] and Brian [Jones] all could sign each other's autographs.
You can find more on the interview, here.