www.politifact.com seems to be a very valuable resource.

I don't know how they decide which claims are false and which are pants on fire.
I'd consider this one to be pants on fire, but they rated it false.

"Three presidents in the last century — Harding, Kennedy and Reagan — all cut taxes during recessions and produced "rapid and dramatic economic recoveries," while two, Herbert Hoover and Barack Obama, did "the opposite.""
Tom McClintock on Tuesday, October 27th, 2009 in a speech on the House floor

Politifact.com notes that Barack Obama has cut taxes already during this recession.

"So far at least, Obama hasn't raised taxes; he's actually cut certain taxes, totaling $288 billion for individuals and companies, as part of his economic stimulus package."

OK so politifact notes that Barack Obama cut taxes during the recession, but doesn't consider the claim that he did "the opposite" a pants on fire lie. What does it take to get the coveted pants on fire rating ?

In the rest of their discussion of Obama, Politifact says that

6. The Obama record isn't settled yet. ... It's true that passage of health care reform would involve raising taxes, and passage of a "cap-and-trade" climate-change plan would represent an increase in regulation.

OK but if McClintok used the past tense as in their paraphrase, then a false claim can't become true because of future events. The claim as stated will remain totally false. Furthermore, the recession is over. The trough hasn't been declared, but GNP rose last quarter. Bills signed by Obama next year won't be signed during a recession unless there is another one.

Similarly, Kennedy didn't cut taxes during a recession. In fact he signed no tax cuts into law. He proposed one in December 1962 during an expansion. The closest recession had ended in February 1960 22 months earlier.

As noted by Politifact.com Reagan's tax cut was not rapidly followed by a recovery. It was enacted one month after the recession began (just barely making "during a recession" and notably before it could have been known that a recession had begun). The trough came 15 months after the tax cut was enacted. That is very un-rapid by business cycle standards. That would be 11 months after the reduced withholding began in January 1982.

I mean the standard seems to be that if any of McClintock's many claims is true, then he is not a bold faced liar. Clearly the key claim is that Obama raised taxes when, in fact, Obama cut taxes. The claims about Kennedy and Reagan are both definitely false.