Current Liferea releases do not handle plain text RSS item content gracefully. If item content is not HTML markup-escaped by the feed generator all text of such an new items ends up in one line without it's line breaks being rendering. This doesn't look very well and makes lists or formatted plain texts unreadable.
For 1.5.x the plan is to solve the problem by auto-detecting the text type of the item description. If it contains no markup than it is to be treated as plain text and all ASCII line breaks need to be converted to HTML line breaks for correct rendering. The critical point here is the plain text/HTML detection. The test implementation in SVN trunk currently only checks for physical HTML tags like <i>, <b> or <a href=""> indicating HTML markup. The risk of this approach is to add additional line breaks to valid HTML content that is not correctly recognized.
If you try 1.5.x/SVN trunk and experience formatting problems with twice as much line breaks or missing line breaks for pure plain text please give some feedback!