In Kubuntu I occasionally get splotchy fonts in gtk applications.
Splotchy-ness can range from slightly annoying to completely unreadable.
As far as I can tell, the problem only occurs in gtk apps.
Below is an example screenshot of Chromium. The text drawn by gtk in the widgets (etc) is blotchy, and the bit of text below that, drawn by webkit, is fine.
And below is a screenshot of my kde-gtk settings. The settings are at their defaults, with the oxygen-gtk widget style and the "use KDE fonts in GTK+ applications" selection checked.
Usually, I can fix the fonts by tweaking the font settings and then returning them to default, but that is not working today, and I would like to find a permanent fix.
Even the "use another font" option is not working with various other fonts chosen -- they are all splotchy.