I found it increasingly irritating that Crunchbang, being based on the current stable version of Debian (Wheezy), is afflicted with a stone-age Firefox or Iceweasel as the Debilians insist on calling it. I decided to again follow the recommended procedure from the Debian Mozilla page, but to no avail: apt would insist that I have the up-to-date version. Searching the web for fellow sufferers, I came across this thread on the Crunchbang forum. Jesus, I've never even looked at the preferences! And sure enough, the Waldorf repository had a pinning priority of 1001, meaning that it took absolute precedence no matter what. After decreasing this value to 990, I finally got what I wanted all the time: an up-to-date version of Firefox (okok, Iceweasel) with automated updates even on Debian stable.
It's really almost embarrassing, but I never even thought about these damned preferences. Well, that's what holidays are for. :)