@Sir Toast: I'm not sure, while Miko certainly wasn't very nice and certainly not someone you should take as a example how to act as a Good aligned person I think she never commited an outright Evil act until she killed Shojo and even that was more about breaking her oath as a Paladin.

Now Redcloak's backstory might provide a better example of "good" characters using any means necessary, but I don't know enough about that to say how it went for them.

Anyway if the person SodaDarwin is talking about commits to many acts that are usually perceived as evil or at least not good - even if they do so in the name of "Good" it seems doubtful they would remain good aligned.

While executing orc raiders (or halfling/elf/dwarf/human/celestial raiders) to scare off others is one thing trying to accomplish the same by wiping out their Settlements to the last newborn is at least iffy.
The same goes for thing like the use of torture to make the evil overlord's slave soldiers change sides and/or give information.

At least I think that the action counts more than the end goal or the target for that matter. One "iffy" act or three don't make you fall to the dark side, but is you are willing to commit atrocities to reach your Goal you have left the path of Good.