"Beer that fell off a truck" has a somewhat negative connotation, but FMHY-listed sites are generally not only free, but also high quality, especially the starred ones. Nowadays when I'm looking for a service to do something I just search FMHY instead of a search engine. Much better results.
“Fell off the back of a truck” is a euphemism for stolen goods; it’s not so much about quality (indeed warez releases are often stripped of ads/launchers/annoyances, rendering them very high quality).