A recent study looked at the use of an injection to make a better first impression.  Here is a summary of the press release, which is interesting and amusing—

According to researchers, first impressions of a person are influenced by facial appearance and improved by cosmetic surgery. They wanted to determine whether or not the use of botulinum toxin A would contribute to a person receiving higher scores on a variety of first impression scales.

Photos were taken of the study participants before and after the treatment with the botulinum toxin A, then the photos were randomly divided into books with each subject represented only once per book. Blinded evaluators completed a survey rating their first impression on various measures of success for each photo in the book.  Findings were that use of the injection improved first impressions.

Plastic surgery does have positive effects on self image, with any procedure such as Los Angeles tummy tuck.  It may be that treated people simply feel more confident and give off this impression.