As a journalist, I have seen how some PR companies directly deal with the Editor-in-chief (or other senior editors) of a publication or a news channel and try to manipulate them if they perceive a junior-level editor/reporter probing the affairs of their clients a little deeper (such a journalist, in my view, would only be carrying out his/her journalistic duties more diligently).
The PR companies that try to aggressively wield a lot of influence on the top media editors include Genesis Burson-Marsteller, Vaishnavi PR, Perfect Relations and 2-3 more.
The media dare not even write about their PR companies as a part of the regular coverage of the role of all kinds of business entities in the economy and industry. But in June this year Tehelka magazine dared and wrote a story on them (you can read it here). It was a welcome torchlight on an evasive bunch of people although I still felt the story was soft.
There is a lot more to say about the techniques used by the PR companies that would do a Goebbels proud. The readers/viewers of Indian media do not adequately know the kind of insights/news/analysis they are missing out on due to such Goebbels'.