[wpietri]

That is a very present question when looking at a lot of think tanks and whatnot.

Personally, I'd say it undermines my trust in a few ways. The broadest is undue weight: if some kinds of opinions are being paid for and others aren't, we're going to hear more of the paid-for opinions. But it also creates more direct incentives to a) say what might be rewarded, and b) once on the gravy train, say what one's sponsors like to keep getting rewarded. And worst, I think, is that money distorts cognition. As Sinclair wrote, "It is difficult to get a man to understand something when his salary depends upon his not understanding it."

So for me, any conflict of interest like that undermines the offered opinion. It's somewhere between hard and impossible to know how much influence is involved.