Clever thinking -- that's just evil.

That is a great idea. I'd try to get the negatives from some source other than Turk though, so they couldn't be found by someone searching for info about the positives.

You're hired. Any relation to this fellow? http://xkcd.com/125/

Just remember to use different accounts & language between the negative & positive reviews. Either way, be really careful to anonymize your tipoff, in case it backfires.