I generate some PDF outputs from a couple of scripts I have running. The fonts looked bad but I chalked it up to some font rendering issue on Linux because of a missing package. Well, turns out I was half right, specifically on the former.
Duck Duck Go quickly took me to a wkhtmltopdf bug report on the issue , which led to a comment with a fix, which led to a Debian wiki article with a conf file for getting Cairo into shape. The supplied fonts.conf on the wiki page worked like a charm on CentOS.