Which is perfectly true. But having to come back and point that out means that he's playing defense. He slipped and now has to fight for his footing when he could be skipping down the field.
Much better to play offense and stick to something like: "You know, barely 3% of that $6.3 mil ends up coming back to me to take care of my family. The other 97% keeps my businesses afloat and my employees on the job - and now Obama wants to dip into that 3%?!?"
They can just point out this...
Inside Mayor Bloomberg’s Extravagant New York And London Townhouses
http://www.businessinsider.com/photos-mayor-bloombergs-townhouses-2011-9?op=1#ixzz1YWsWzYxC