We run this free because it is how we decide whether to take an engagement, and because a meaningful proportion of accounts we look at have one or two specific problems rather than a need for ongoing management. Telling someone that is more useful than selling them a retainer.
The single most common finding is not a bidding or keyword issue. It is that conversion tracking is measuring the wrong thing, double-counting, or not firing at all, and the account has been optimised for months against numbers that were never true.