Under the "Your Site on the Web" section of GWMT there's a sub-section named "Keywords"-
Keywords Below are the most common keywords Google found when crawling your site. These should reflect the subject matter of your site.
But it's not showing accurate. It's like my site is about weight loss images and it shows "weight" keyword with full significance, "images" with a bit less significance..but what the heck there's no "loss" keyword in that list? I used frequently the keyword "weight loss"...what's up with all this..is this some kinda bug? o_O
in general i have found the keywords sub section in gwmt to be fairly accurate. when i see it showing unrelated & inaccurate keywords in that list it almost always ends up that the website was hacked and had hidden text inserted into it.
i would suggest you use the gwmt tool to retrieve your pages as googlebot to better understand the words that google is seeing and indexing. you may discover that your website is lacking certain keywords or overusing some keywords.