This page discusses what to do (and what not to do) when faced with the "Race Card" smear. That's followed by some examples of politicians and others playing that card .
Note that I'm using "playing the race card" to refer to smearing someone or some thing as racist when it's not warranted. In some cases it is warranted; this entry is only about the cases where it's just a smear.
What Not To Do
If you're smeared with the race card, the first rule is: don't repeat the smear. Somewhere around 99.999% of those smeared with the race card violate that rule and help their opponents, such as by repeatedly claiming "I am not a racist!" The problem is that the more someone denies it and repeats the smear, the more others will believe there's something to it. Many of those observers will simply not hear the "not" in "I am not a racist!"; they'll hear it as "I am a racist!" Others who are smeared will recite stock phrases like, "some of my best friends are [fill in the blank]". That just makes it worse. Others, such as the witless leaders of the tea parties, make things *even worse* for themselves by supporting far-left concepts like quotas and tokenism. The far-left is the main perpetrator of the race card, so giving their concepts more power is the last thing anyone smeared by the race card should want to do. The teapartiers are led by those who only care about money, so they have no background in or real desire to oppose the far-left on social issues. Don't be like them.
What To Do
The race card - when used as a smear - is *an opinion*. It isn't a statement of fact. Therefore, the way to combat it is to show that the formation of the player's opinion is faulty. There are two basic ways to do that.
The first is to engage the opponent in debate. If you have a strong case that whatever you did is not in fact racist, then make that case (note again: don't repeat the original smear). The goal should be to *discredit your opponent to his or her supporters*. Almost all of those smeared with the race card and who try to make an argument that whatever they did wasn't racist, only make an argument that appeals to *their* supporters. Preaching to the choir does not work in general and it doesn't work in this case. If you're smeared, you have to make an argument that your smearer's supporters will understand.
The second is similar to the first: you have to show your opponent's supporters how your opponent isn't credible by catching your opponent in lies, misleading statements, or in general making bad arguments. In most cases, that will be about other topics. For instance, if you're smeared, look back through your opponent's past statements about other issues to find instances where they weren't truthful. Or, make note of future instances where they aren't truthful about other topics. In any case, you have to convince your opponent's supporters that your opponent can't be believed. The race card is an opinion, and you have to show your opponent's supporters that your opponent's opinions are faulty.
 There are almost 10,000 entries here, compiled since 2002. Tagging was only added recently and, since playing the race card is a frequent occurrence, it will take a while to add even a small subset of the examples here.