It's the product of people who've interviewed people in Iran over a long period of time, not just foreign journalists who jet in and out. That's why ICG analysts are so highly paid.
One caution though, foreign diplomats here can be pretty out of touch. I've been to this one Western consul's parties a lot and he earns an order of magnitude more than I do. Of course he's out of touch with what ordinary people think, it can't possibly be otherwise.