After watching a TED presentation on External motivation, which stated it did more harm than anything. I was nodding in full agreement and trying to think of one job where it was not true. The only job I came up with was sales, I was just not sure for this one. I would really like to see a one year after report on this, this should be telling. I think it will prove commissions are not working.
BTW the TED talk is http://www.ted.com/talks/dan_pink_on_motivation.html