Few days back there were reports on Google Webmaster sitemaps tool having a bug that shows old data. At WebmasterWorld, Vanessa explained, "As Googlebot recrawls the site, you should see the common words table updated to reflect the new content."
Further, Google Sitemaps blog post Unexpected Common Words explains the reasons for occurence of unexpected common words in the report. These are:
- Googlebot hasn't crawled all pages on your site. – If words on particular pages are missing, make sure that those pages are being successfully crawled. If those pages are not yet in your sitemap, adding them will help guide Googlebot to those portions of your site. Also, make sure that you link to the pages of your site from within your site (for instance, by using an HTML site map).
- Your site has changed since we last crawled it. – If you have just redesigned your site, made significant content changes to an existing site, or purchased an existing domain and changed the contents, the data will not be updated until Googlebot has successfully crawled the new or changed pages.
- Googlebot is unable to re-crawl modified pages.- Googlebot may be unable to access your server due to network error, or may encounter a server error when trying to load your pages. Make sure that your server is responding properly to incoming requests.
- Your site is not being crawled. - New sites may take some time to be fully crawled. Read through our information for webmasters for more information about our crawling processes. Also, make sure your site doesn't violate the Webmaster Guidelines.