Sure it will be hard to determine if the improvements are due to the cause of SEO or some other update, but using revenue as a metric has the same issue.
(Ideally one would use a "difference in differences"[1] approach, but it could be difficult without good comparators).
However, there is another problem with metrics. Sometimes, it is too easy to pay too much attention to vanity metrics that won't add anything to your bottom line. Will moving from a 25th place to 1st place for a search help your business? That depends - does that search generate traffic, and does that traffic generate revenue? On the other hand, increasing revenue is never a bad thing.
I'd argue that unless decision makers have too much time on their hands, they're better off focusing on metrics like revenue than metrics like search results. Validity will be a problem across all metrics, but at least there isn't a tendency to optimize useless metrics.
I think that's what the previous poster is getting at - getting a lot of revenue isn't hard if you're willing to throw core parts of your business under the bus (say, profitability).
More generally though optimizing for any kind of financial target (whether revenue, profit, or otherwise) can still be gamed like any other metric.
Your salesperson promises the moon to a client, closes a bunch of deals, looks great, and your company takes on a boatload of liability in the process - for example.
Or, to take a real life example - drop the price of your software to 99 cents and ride a huge sales wave but find your clientele unwilling to pay anything more than 99 cents from then on (hellllo mobile apps).
Lots of ways raw revenue/profit isn't by itself a great metric.
Oddly I was reading how Buffets first insurance company was focused on writing profitable premiums only - to the extent of seeing shrinking business. It was unusual then and now, so I do take your point.
1. The keywords you want may be worthless 2. Google/Bing/Yahoo stopped sending the keyword data about a year ago (so you have almost no insight into what keywords did what
What is important is driving meaningful traffic. This usually means increasing visits that increase revenue.
Here is the hard part, besides ecommerce sites, most businesses do NOT track at the level needed to know.
Even if you educate people, there is a tiny set that actually care to track and an even smaller set that actually put in the effort to do so.
A lot of people still care about the vanity side. "I am #1 for <keyword>"
Pay for Perforamce marketing only works if you close the loop. And even then it's a hard to do and may not be best for everyone
To me, it does sound like your friend was a victim of fraud.
By the way, she does not sell a product, she sells a service (herself) and that's a little more difficult to track.
Let's say I am selling a saas service, Facebook for dogs. I advertise on keywords like "share my puppy pics". Each keyword hits a different landing page. I track users with a cookie
Is there any more or less to do?
Disclosure: professional marketer and former FT SEO who is tired of people getting fed snake oil.
A friend's analytics showed an amazing number of visits for a tiny site. While traffic was up, it did not lead to new clients. She fired the company she'd engaged for SEO/SEM because they kept raising their rates as traffic milestones were reached (hundreds of dollars a month).
Immediately after terminating that relationship, she noticed a 95% drop in traffic and panicked (see http://i.imgur.com/WwJ0vYo.png ). I was asked to fix it for her. One look in the referrers showed that this 95% all originated from China (ads.acesse.com) and was useless/fake (very few page views, very short durations). While we have no proof to support a lawsuit, the timing was too much of a coincidence to ignore.