If you are as easily offended as those delicate creatures, the Repulicans, you might do well to read the whole quote before jumping to conclusions.
When Barack Obama made the remark about lipstick on a pig, he was talking about John McCain. He was essentially saying that although John McCain kept saying he was for change, he was actually for more of the same on "economic policy, healthcare policy, tax policy, education policy foreign policy and more Karl Rove style politics". It was then he started to talk about how you could put lipstick on a pig but it was still a pig.
A cynic might say that the Republicans knew he'd landed a blow so they started getting all hysterical about him being sexist and attacking their gentle, sensitive little pit bull.
Did we hear the Republicans complain when the Swift Boat people actually smeared John Kerry's distinguished record in the dying days of the 2004 campaign?