I'm starting to think its an epidemic..

I have to question how you go about changing these charging system components.. Do you always disconnect the negitive battery cable ?
You can buy a new regulator and kill it before you get it bolted to the firewall. Install electrical stuff and make sure its chassis grounded before making wire connections. Same applies to those amp gauge terminals. connecting them together rules out the gauge but if sparks fly while you're tinkering , there goes another regulator or fusible link or both.
The altenater itself is grounded but its mounting hardware but enough paint could interupt that ground too.