I have a number of data only PDFs that users find highly valuable on a few of my sites. All of those sites were hit by Panda 1. The only real low-quality work on those sites are these data-only (numbers) PDFs, thousands of them.
Would a robot.txt disallow of the directory of PDFs re-establish quality?
With HTML I usually just “noindex” and robot.txt disallow, but PDFs don’t allow for that option.
I have a number of data only PDFs that users find highly valuable
Why are they considered by u low quality when the user finds them of high quality, or are a few of them high but the vast majority are considered low? To add them to a robots.txt file you will need to add the PDF's into a new folder called PDF then the whole folder can be blocked if this is the way you want to go.
If you block the bot from crawling files via "robot.txt" will G ever count those towards the quality score of your site? I'm just worried about sometime down the line getting hit by Panda if 1/10 of my site is data driven PDFs.