Sen. Mary Landrieu (D-LA) has been shaving ethical corners lately. First was the report that she actually does not own a house in Louisiana but rather lives on Capitol Hill in a $2.5 million home. Now, she has returned $33,727.02 to the U.S. Treasury for improperly paying for chartered flights for her election campaigning on the government's dime, instead of her re-election campaign -- for the last 12 years. "The review I ordered last month found these mistakes stemming from sloppy book keeping," Landrieu said in a statement. "I take full responsibility. They should have never happened, and I apologize for this. A new system has been established that has been successfully used by a number of senate offices to provide a safeguard from this happening in the future." Landrieu is upfront and honest about a $33,000 mistake because, hey, the bill is less than the average American salary -- pocket change -- but why did she not use newly established system used by her peers? Probably because integrity isn't an issue. More…