My TR003 is rather good , highest I may have seen is 4.21 [ and yes - any charger can overcharge - just depends on the luck of the draw ]
Aaaa yes , Open voltage ... not really an issue ...
Dry joints = possibly poor contact - yeah , they could ...
Some components get warm hot , and dry out solder joints [ Older TV's used to suffer from this a lot , as did CRT monitors ]
Under charging - no not really , but if it undercharges too much , then the battery may have its life shortened when used and drained to low ...
Generally I try to charge my batteries before they reach 3.5v , I aim for 3.8v ....