 We don't call people scrupulous very often, though. It is a word, so it's not quite what linguists call an unpaired word. Words like disgusted, unscathed, or overwhelmed, where we don't use them without the prefix. Disgusted. Unscathed. Overwhelmed. Maybe we don't use scrupulous as much just because there's less opportunity. Maybe if more people were more scrupulous, we'd use the word more, and then I wouldn't get so confused. But we're using it today because scrupulous is our word of the week.