The latest McCain attack ad is a prime example. It seriously distorts—lies about, would be more accurate—Sen. Obama's position on a sex education bill that came before the Illinois legislature several years ago, making Obama appear to have position on that issue that he does not have.
Here's part of an article from today's New York Times, which deconstructs the McCain ad and refutes the charges:
Ad on Sex Education Distorts Obama PolicyIt is a misstatement of the bill's purpose, therefore, to maintain, as the McCain campaign advertisement does, that Mr. Obama favored conventional sex education as a policy for 5-year-olds. Under the Illinois proposal, "medically accurate" education about more complicated topics…would have been reserved for older students in higher grades.