I agree with Silenia.
I've save scummed when fat fingering has caused me to light a fire inside my cabin rather than get stuff, and I've also save scummed when my dog drowns while I circle a single tile lake inside my trap fence which, in my view, is a buggy behavior (but I try to avoid it happening by leashing the dog when there's weak ice about).
I know backup saves provide a temptation to save scum to undo stupid decisions, but to me the crucial difference is whether you want to save scum due to a bug/accidental key press that should never happen in reality, or whether it was a stupid decision/bad in game luck (like my last character's death: poor judgement followed by very bad luck, hopefully leading to slightly better judgement for future characters).
Ultimately, though, you play the way you want to play, and use save scumming the way you want to, tempered with your knowledge of how good/bad you are at resisting temptations.
UrW is written to be played without save scumming, but it's also written to be played without crashing. Crashes happen, so backup saving is an appropriate counter measure.