I would prefer that we strive for no lies whatsoever in politics, but I know that such will never occur. Doesn't mean we shouldn't go for it.
As to your opinion that Pres. Obama has lied a lot less than Pres. Bush did...well, he has had less time in office...and it is and will likely continue to be a matter of opinion. Even if Pres. Obama is proven to have never said anything true at any time while being recorded, some people will still have a supporting opinion.
Same goes for any politician out there.