alternators burning up

Years ago a friend had a chevy nova w/350. Repeatedly loosing alternator, regulator, or both. So he finally brings it to me. While in just initial look over, no tools or testers out, I noticed the ground cable screwed to block has a good wrap of oily loose electric tape on it. I gave that wire a slight tug and it pulled right out of the bolted lug/terminal. Replaced that cable, went ahead and upgraded him to the later models internally regulated alternator, no more problems.
Bottom line, poor connections are the typical culprit. They aren't always so easily found though.