Dent in deep-V rim

given aluminium's fatigue life i doubt that this is a safe practice. i think i would rather have the peace of mind that a part is not likely to suddenly fail, a disintegrating rim can have fairly catastrophic results

I understand your concerns but really, rims are tough. As an experiment I have tried to bend/prise apart/smash with hammers, wheels and rims which were "too far gone" even for me. Even cheapo rims with pinned joints are really strong, you can get the join to split but it wont fully separate easily at all.

If its a serious dent there will always be a little dip in the wheel which will be extremely irritating when ridden at speed, might set off speed wobble even. This would be the major concern, that and hindered braking. Those are the reasons I would consider a rim dead.

Do not forget that every rim was bent into a circle in the first place.