Whatever the rule is, we have to insist that there be one rule. Right now, we have one rule for Democrats ("Let someone else prove it, then maybe, maybe, maybe maybe we'll run it") and one for Republicans ("If there's an allegation, it's a story").
What you suggest is only fair. But, unfortunately, the media has not been fair within the memory of man. We need to find ways to deal with the bias--since the bias is clearly for the Left--but in that, the field of spreading gossip is the least of our worries. Properly handled, the spreading of gossip will backfire on those who spread it.
If Bush had been better advised in 2000, the last minute DUI smear--what else was it, a minor over the line infraction 24 years earlier, when he was only apprehended because he had taken precautions not to endanger anyone--could have been a tremendous opportunity to garner a couple of million extra votes.
The way you play such a smear is to let it build an audience, then go on TV to answer. People who do not like you, tune in to watch you squirm. But you do not squirm. You admit (in the case of the DUI) that you were not perfect at 24. That takes 20 seconds. Then you deliver a stirring 28 1/2 minute speech on your vision for America. You can only gain from the approach. (Nixon's 1952 "Little Dog" speech would be a well known example of the technique, althoug there he had to spend several minutes on the actual charges. Bush had a better opportunity to really use the smear to advantage.)
William Flax Return Of The Gods Web Site