Changes

The statement  

The statement  

:'[[Shepard Fairey]], designer of the official Obama hope and change logo, is more known for his anti-American and pro-communist themes'  

:'[[Richard Wagner]] was an opera composer much admired by the Nazis'  

might be considered an ad hominem attack on Fairey's art or Barack Obama.  It may or may not be true, and in some contexts might be a relevant comment.  But if someone says it in order to suggest that Obama or Fairey are bad people, then it's an ad hominem attack, because whether some bad people liked Fairey's art is not a relevant comment on its quality or that of the positions of Barack Obama.

might be considered an ad hominem attack on Wagner's music.  It is true, and in some contexts might be a relevant comment.  But if someone says it in order to suggest that Wagner was a bad composer, then it's an ad hominem attack, because whether some bad people liked his music is not a relevant comment on the quality of his music.

== Ad Hominem Not Always Fallacious ==

== Ad Hominem Not Always Fallacious ==