You're nitpicking the term "journalism" here, but even in casual conversation if a friend went on and on about how great a company was and then I later found out that they:
* Got paid a referral fee if I signed up
* Owned shares in the company
* Even was roommates with the founders/CEO but failed to mention it
I would trust that person less going forward.
If you want to be perceived as trustworthy, then you shouldn't say things that you have a hidden interest in saying.