GWT - 'Content Keywords'

[cube101]

Hello,
Using Google Webmaster Tools to look at my content keywords (wanting to see what google is finding as the top most important one on my site)
it seems to be just taking words from a number of product pdf download that i also have on the site rather than from the actual webpages... this means most of the top words are pretty generic and not my targets. My question is, should i be 'no following' or blocking the crawl of the pdfs? and are there any tip on improving which pages google is sampling my keywords?
Thank you.

[Test-ok]

Find out what Google is sampling and move forward from there.

[cube101]

how would i find what google is sampling?
if i use - site:mysitedomain.com - and look at the top 10 pages returned is this a better indication of the pages google sees as the most important on my site?
thanks