(With thanks to MRM, who both inspired and contributed to this post)

Hell if I know. When someone I know reveals themselves to be a liberal I mostly just hand them a tissue to wipe the foam off their mouth. Often I spike this tissue with chloroform. Don’t thank me, I do it for the greater good.
But in the event that you find yourself in that most awkward of situations (for those not following along, that would be discussing politics with a liberal), what do you do?
This especially sucks if this person is:
Your Client
Your Boss
Your Kid’s Teacher
Your Kid’s Friend’s Parent
Your Mom (and here I am referring specifically to YOUR mom…my mom would never be a liberal. I am offended you would even think that)
Or, really, any liberal you can’t stand listening to anymore, but to whom, because of the circumstances, you are forced to be civil (and here I am NOT referring to your Mom, because even if your Mom is in fact a liberal, of course you are not being forced to be civil to her. She’s your Mom. Geez.)
So when going full on Honey Badger is not an option, what do you do?
No, seriously, I’m asking. Treeper MRM and I have been talking about this because she runs into this a lot (I think we all do)…you are talking to someone you can’t afford to/don’t want to alienate and all the sudden they start spouting off any or all of the following:

• Sarah Palin is stupid.
• George Bush is stupid and evil.
• Barack Obama is doing the best he can with the mess he inherited from the evil and stupid George Bush.
• Healthcare should be free for everyone.
• Rich people should pay more taxes.
• Fox News is biased. Also stupid and evil.

You get the picture.
A lot of times I just make my eyes really big and go: “Oh my goodness, aren’t you just the cutest thing with your little lefty socialist ignorant worldview!”. Then I pat them on the head and hand them the above mentioned tissue.
You can see how this would not be practical in a lot of situations.
So I’m hoping you guys can help. What do you do when you encounter this? Is there a polite, respectful way to disagree without endangering your career, your child’s social/academic life, or a treasured relationship? When is it right to just change the subject and when is it okay to share your own beliefs? And what facts/sources do you use to back up your points? Do you have a good website/pundit/historian/economist that you trust?
I know we’ve kicked this around in the open threads but this post is dedicated to your perspective on dealing with liberals that you can’t just yell at/condescend to/slap/divorce. Especially appreciated would be some polite rejoinders that might just provoke actual thought on their part.
Extra-especially appreciated would be hearing from former libs/Dems about what worked to change them.