Here's a small illustration of the difference that a user friendly format can make.

For my first SEO project, I updated a friend's site to comply with web standards and make it SEO friendly. I was of course eager to see the difference this would make in rankings and traffic. I was expecting to see some improvement, but I was surprised at how quick and dramatic the change was.

Specifically, I wasn't expecting to rank number 1 in Google SERPs for one of my keywords just one week after the new site was posted. But there it was in blue and white: a new page I had added to my friend's site ranked first for the words "bird consultation".

Besides ranking #1 for my friend's name and the name of his business (even though he hadn't ranked at all before for either one), I had expected to rank first for "flying ring bearer". The only competition was someone in Britain who used white owls instead of parrots. And jumping from #450 to #17 for "bird shows Orange County" wasn't too bad either. But it shocked me to rank first right out of the gate for what looked like a competitive keyword.

Spot #2 was held by a PDF report from a consortium of Fish and Game agencies with the title "Nongame Migratory Bird Consultation".

Three hours later, when I had enabled the screen capture software and wanted to take a picture of my accomplishment, I discovered that I had slipped to the #3 position. Number 1 was now held by the Fish and Game site, with a sub-listing in #2.

 

Closer inspection revealed that they had added an HTML version of the same report, which assumed the #1 spot. Number 2 was a sub-listing showing the original PDF page.

Unless I'm missing something, I can only conclude that it was the switch from PDF to a friendlier and more standard format that resulted in the promotion of the site's rankings. The HTML is readily crawlable. Now, I'm speculating that Google automatically subtracts points for anything in a PDF file without an HTML counterpart. When only the PDF version was posted, the SERP had a link to a Google-generated HTML version. But I'm guessing they don't crawl those looking for keywords the web developer was too lazy to put in their HTML. Does anyone know anything about this?

Either way, I'd call this an illustration of the maxim that making your content both user friendly and robot friendly will greatly improve your rankings.

I think I'm going to enjoy this new profession.