Micah Cohen at 538 reports on Politifact’s grading of the veracity of 2012 GOP Presidential candidate statements. Probably the most important caveat to note is that it just grades those statements that piques Politifact’s interest; so there is a sampling bias.
That said, Ron Paul and John Huntsman, come off looking best in terms of truthfulness. More than half of what Ron Paul said was graded as “true” or “mostly true.” Huntsman scores 4 of 7 in those categories and without any “pants on fire” or “false” ratings (much smaller sample size, however.)
Michelle Bachmann, on the other hand, came off looking worst. 80% of her grades are “mostly false,” “false,” or “pants on fire.” Rick Perry doesn’t do well either – about 50% “mostly false,” “false,” or “pants on fire.” Mitt Romney is in the 36% range for those categories.
By way of contrast, President Obama is at about 29% in these categories