Main Question:
At which point can I trust external, unofficial repos? Are there security implications for blindingly adding third party repos to a workstation? However, I've been very suspect of including non-offical repos.
Background and my particular case:
I'd like to install a Juce. From what I understand, this is a stand alone utility to host VST (virtual instruments used in music production). I've found what appears to be it's source on github and have tried to compile that in a throw away VM. However, after receiving an errors on install (to which I may open a ticket here or on github later), I was curious to see if anyone had packaged it for Ubuntu.