I was an analyst for many years at a pay-to-play analyst firm, and like many of my peers, I strove to maintain my personal integrity, despite the many, many pressures I felt to say the right thing. At the end of the day, I found it was impossible, and I quit doing that kind of work.
It wasn't the overt stuff. Despite many, many suggestions, I never, ever wrote anything that I thought was untrue. But in this business, the nuances matter. You end up giving people the benefit of the doubt, when you shouldn't have.
You also found that it was impossible to call a spade a spade. If some poor guy plunked down $20,000 of his savings to get our firm to say that his nonsense software had some merit--this really happened, the company now long-gone--it was hard for me to look the guy in the eye and say, "No way," and as for my boss, well, he's the guy who negotiated the deal. So you try to thread your way through with phrases like "interesting" and "still some way to go."