Was it all a scam?
** SPOILERS **
Does anyone else think that the whole thing might have been a scam by Auntie Mei? She claims to be in her 60's, but the only proof she gave was an old photo that could have easily been faked. Mrs. Li and her other clients would be so desperate to believe that her dumplings really did have rejuvenating powers that they would believe her story that she was really in her 60's.
The fact that Mrs.Li didn't get any noticeably younger to us (although her friends noticed a change that could have been because of her increased self-confidence), perhaps point to the fact that she was in fact just an unscrupulous opportunist who preyed on people's vulnerabilities to make a living.