Product descriptions are stored as HTML in the database, so whatever is HTML formatted there will render on your browser.

What you may care to do is "clip" a copy of a particular product description HTML off one of those data dumps you did - and then "paste" it into a HTML Editor to see how the browser is interpreting it.

If you're getting too many line / paragraph breaks, it could be an excessive quantity of <BR /> tags, or <P> tags.

You may also have some settings in your stylesheet that affect body text, so check your CSS too.