I was just doing an exact phrase match on my site to check out scrappers and noticed that google didn't return a result. After some trial and error, it came out to be the span tag.
Not sure if I've described the issue correctly, so here's an example:
"red widgets"
will not match your page if the post content is
<span>r</span>ed widgets
To match the same you'll have to try
"ed widgets"
So are my (anyone's) rankings getting hurt for such key phrases since they begin with a span (I use it to style drop caps) like:
<span class="drop_cap">T</span>his is a drop cap.