Does Impact Factor reflect the quality of a journal?
No.



To answer Paul's comment:

The title of the post asks about journals.  For a well-worn list of criticisms of Impact Factor as an indicator of journal quality, see the Wikipedia article and the sources it cites.  In many disciplines, important papers receive most of their citations well outside the IF's two-year window.  Raw citation data can be manipulated by editorial policies, some more nefarious than others, or even by individual papers.  Thomson-Reuters' calculations of Impact Factor are not reproducible, even using their own citation data.  Et cetera ad nauseam.  But most importantly: Having lots of citations is not the same thing as quality.

The body of the post asks about journal articles.  Impact Factor is (roughly) the average number of citations to all papers published by a journal in a given time window.  Even if it were a reliable measure of average quality (which it isn't), it would say nothing at all about the quality of any individual paper.