I remember during one of my campaigns someone called me and told me that one of their neighbors they suspected was taking part in an abusive personal relationship had a sign of mine in their yard.  He told me that because this neighbor was supporting me, he wouldn't be voting for me.  My response was that I can't perform a background check on everyone that is actively supporting my campaign - or know everything there is to know about a supporter.  There are many reasons why people vote for someone - if they are a registered voter they can vote.  Is it the candidate's responsibility to vet their supporters? 
I just don't know where this line of thinking is taking us...period.