(G3, I believe, I don't recall and don't know all the models. Sorry.) [....] He had plugged his G3 into one of the (micro/A/B/whatever) USB plugs from his other "standard" USB-charging phone
I had a friend who bought what he believed to be a genuine Apple charger and fried his tablet, the cheap stuff will always be there wether you use an Apple connector or the standard USB version.
Your story would be more interesting if you knew the specifics, i.e could supply make and model of both charger and phone.