The UKIP posters on the way into Billingshurst have had swastikas painted over them, which is somewhat overdoing it IMO. But I know some people do get wound up by political views they disagree with.
In the safe Tory seat where I live there are very few political posters. Yes, there are the famers' posters, but in individual houses very few. On houses in my constituency I've seen two Liberal ones, 1 UKIP and nothing for anyone else.
But go to Lewes or Eastbourne constituencies and things...