DMK got burned more than usual in 2011. And nearly 40 constituencies had a vote difference of 500 to 2000 votes. Swing votes as they call it. People were fed up with the way TN govt operated. Chennai floods added to ADMK woes.
I personally knew a guy who opened a factory in Guindy industrial estate for 4C, suddenly got his industry sealed by authorities. AIADMK partymen demanded 1C for letting it open. The poor guy had to bargain and he had to shell out 40L finally to open his business. This is the case all over TN. Many industries wanted to invest in Chennai and moved over to Sri City cos of this corruption.
DMK did corruption in things not affecting jobs and industry. Like mining, cement, 2G etc AIADMK on the other hand dont have educated professionals who can do high level corruption