For example let's say you go to disarm a trap, and fail. The trap probably goes off and you take some damage. It you load and reroll on the trap, that's one version of save scumming.
Maybe you have a particularly hard battle. You enter the battle and a specific character doesn't roll high enough initiative or maybe their first attack/debuff fails. You load until a certain character or debuff hits, that's save scumming.
Maybe you have a few different dialogue choices. You want to ensure a specific reaction/outcome. Maybe you need to roll to make that happen. You load until that happens.
Maybe you're given a dialogue choice. You think your character is being snarky. You think you're being playful with your characters. Turns out you're wrong. You load and pick a different option.
Maybe you're mid battle. You realize you're going to lose. Maybe you'll survive with one character, but realistically you'll all die. It's not worth playing another 20 minutes just to die. You call it and load an old save.
Maybe you know you're going to win a fight. You only have enough resources for one fight. Maybe a character will die that you can't revive without going on a long adventure. You can do it. It's going to be easy. But it's going to take a bunch of time. You figure you aren't that far into the battle. Reload.
It's ultimately a single player game (yes, you can play with friends). If you're having fun, save scum all you want. If you think the game is "too easy" maybe save scum less.
Consider it you do save scum, you might be missing out on something. A character who always succeeds might not be fun. A character should have flaws. Going into a battle under prepared could make things more interesting.
Long story short, no, people who despise save scumming still reload an old save. Unless you're playing "hardcore" (you die, you die) you go back in time. You save scum.
Yeah, your last 3 examples are the ones I usually reload for and don't feel bad about. I try to avoid save scumming just to redo rolls, but in particular, some dialogue choices are really poorly explained. I don't feel guilty reloading for those because I don't think they would happen with a human DM, where I get to actually word what I say and can get clarification if needed.
There was one battle against a blatant evil character where they tried to negotiate when they were close to death. The dialogue choices were confusing and I accidentally somehow chose an option that would have let them go. I ended up reloading and doing the whole battle again just so I could kill them, as intended.
The difference is that if you lose in battle the game can't go on, your only choice is to reload or start a new game. Making a choice in a dialouge is not the same thing at all and will never force you to reload. I always try to live with my choices even if the outcome is bad, it's all part of my own story.
I encountered one the other day and it was the first time I've ever seen this in BG (or any other table top game). I failed a check that resulted in an instant TPK. It utterly hilarious honestly. I'm really glad I failed it just for the experience. Thankfully I obsessively quick save.
I load when I enter fights I don't want to take. This is not because of the fight or it's outcomes, it's because it takes 5+ minutes to conclude the engagement and often times your party gets owned.
I don't have much time to play so I prefer to load out and make a marker and just deal with that at some point later.