You know...
After reading the majority of your posts I thought I would disagree with you on almost anything. Scarily enough I find myself agreeing with many of your comments, this one included. I've never tried to be anyone other than myself in an interview or a job. I supply the employer with what they ask for and hope they like me. If they don't like me or my attitude, perhaps I would be happier some place else anywho. No matter if I'm at work or at play, I can guarantee you I am the exact same person.
This part in particular I like:
If you are naturally a bummer and miserable, you may be a good candidate to look inward and adjust your sttitude
You need to fix yourself instead of worrying about what your potential employer wants if you're that person.