Norman Fowler says that politicians shouldn't use the private lives of their opponents against them in the way that they do. Fair enough.
If they wanted to, they could go further. They could recognise that a lot of allegations of impropriety (bribery, favouritism, etc) are wheeled out strategically. They should agree to park and refuse to comment on a story once it's been referred to an investigating authority. They could even see if the press could be coerced into doing the same.
All new allegations against the person concerned should be submitted in private. An informal version of sub judice. It would reduce the number of vexatious and petty allegations and it would help to improve the standing of politicians in the public's eyes.