Time recently published ‘A Brief History Of: ‘Putting Lipstick on a Pig” noting that many politicians have used it publicly, including Barack Obama, John McCain, Dick Cheney, and both John and Elizabeth Edwards.
The Urban Dictionary’s definition of “lipstick on a pig” is:
slang for when someone tries to dress something up, but is still that something. usually used on ugly broads, when they put on a skirt and some lipstick and well, they still look like the same digusting pig.
–Ann Bartow
Personally, I prefer “silk purse from a sow’s ear”, which at least doesn’t originate as a disparaging description of a woman’s appearance. Though “lipstick on a pig” isn’t quite as bad as the British equivalent, “pig in knickers”.