Some of my nodes have an empty teaser field so when I visit a taxonomy page, you cannot see any of the body content. Only when you click on the node title to view the full node can you see the body. Why does this happen? I fix this by manually editing my database and adding content to the teaser field of the node_revisions table but it's troublesome to fix nodes this way.
This problem might be related to the WYSIWYG editor you're using. Some of them output a lot of redundant code, so you don't get anything or a bunch of white space before content on teasers. Try using the 'Edit summary feature' that comes with Drupal corer to fine-tune teasers (or you could always have a new teaser text field). Most of the WYSIWYG editors come with a Teaser button, so you should use that.