Table Summary doesn't match table. The table has three columns, and the table summary describes it as if there were only two.
The current table summary says:
Table holds a list of sites that you have joined. Column 1 holds the site title and a link to unjoin. Column 2 may have a description of the site.
A more correct table summary would read as follows:
Table of sites that you have joined. Column 1 holds a checkbox that can be used to mark sites you wish to unjoin. Column 2 has the site title as a link to the site. Column 3 has a description of the site if one is available. After selecting sites you wish to unjoin, use the unjoin button located below the table to unjoin them.