Why? Because it would be foolish not to.

1. The Daily Mail is read by 4.6 million people, making it by some margin the most read daily national newspaper. And that’s without even getting into its website, which is now the most popular newspaper website in the world. You can’t be interested in what the media is saying and ignore it.

2. Very large numbers of Liberal Democrat voters read it: around 576,00 Daily Mail readers voted Liberal Democrat in 2010, a number only topped by the 796,000 or so Sun readers who voted Liberal Democrat. That Daily Mail figure is more than the equivalent figures for The Guardian and The Independent put together.

3. The Daily Mail invests heavily in its journalistic resources. Whatever you may think of how they write-up their stories, its journalists frequently break stories due to having the time to do the old-fashioned legwork. Its record in breaking stories about dodgy Labour donations under Gordon Brown was a classic example: the Mail unearthed the story because it sent journalists door-to-door calling on Labour donors until they found something.

4. And then there’s the question of how the stories are written up… In my view, all manner of stories end up being written up in a distorted manner, but you can usually do a reasonable job of extracting the truth from a Mail political story by:

Ignore the headline: it often exaggerates so much for effect that it doesn’t really match the story.
Read the first line to get what the story is about, and then read the story from the end upwards: there is often a defence included in the story towards the end which undermines what goes before. Although I’ve read plenty of their stories on political topics which I know about and thought the headline and first-half of the story was distorted, I’ve not (yet) come across one of these where the second-half didn’t provide the explanation as to why the story was wrong.
Watch out carefully for who is quoted to support the story. The usual structure of the political scandal story is to have a quote from an opposition politician, often calling for an inquiry. There are some, from all parties – such as Vince Cable in the example linked to above – who have a track record of only calling for an inquiry or condemning someone when they have very good grounds to. Then there are others seemingly will happily condemn something based on the merest prod of encouragement from a journalist.
Apply these three tests and you can do pretty well at getting to the truth of a Daily Mail political story. I’ve seen plenty of devastating demolitions of Mail political stories, but those have all been ones where these three tests had warned me already. Of course, one day there’ll be a story that breaks all these rules, and all this leaves aside the question of what stories to choose to run in the first place…