It's a complicated election. I looked through the literature a while back after a Lib Dem friend claimed that the worst smearing probably came from John O'Grady the 'Real Bermondsey Labour' candidate. His literature is fairly mild mostly making inferences to Tatchell's 'militant' tendency so it doesn't compare the Simon Hughes' 'Straight Choice' or a cartoon of him punching Tatchell in a boxing ring.
One issue is that the seriously nasty stuff didn't make it into leaflets (quite an old fashioned dirty dirty campaign in that respect). O'Grady apparently spent some of the campaign singing homophobic ditties on the back of a beer cart.
... and at least one of the worst leaflets ("Which Queen Will You Vote For?") was anonymous.