One maddening thing about The Acceptable Discourse in DC is that there are people who are paid to lie. It is their job to lie. The bothsides view of this is, well, it's everybody's job, so whatever. Still there's a difference between, say, Big Tobacco lying, and The People Who Fight Against Big Tobacco lying. Let's just stipulate that Both Sides lie. But the financial incentive for the latter to lie is... um, I guess if you're a spokesperson your job is to be an effective "advocate" so maybe you earn your salary by lying if necessary?... but there isn't a billion dollar industry behind going after Big Tobacco. The Big Money is not so big.
The incentives to lie are not identical, so even if none of us are pure, having Both Sides coverage of issues, where one side is The Committee On Feeding Your Children More Lead, and the other side is Save Our Children From Lead Poisoning, means you're going to get a bit more dishonesty from the former.
Related: newspapers really don't have to run PR pieces pushed by the lobbying firms of billion dollar companies. It's just information laundering.