Using the TinyMCE editor and the moodlenolink function it's easy to create awful xhtml.

It's possible to select (multiple) block-level elements (e.g. p tags) and wrap them in the <span class="nolink"> this isn't valid xhtml.

Also... as I've just posted a fix to get nolink working in the mediafilter (http://tracker.moodle.org/browse/MDL-4330?focusedCommentId=107764#comment-107764) it's typical that we want to wrap the entire link not just part of it.

I have a fix - will post a comment with a link in a sec.