Interesting topic. But language has no quantitative standards, so I guess everybody has to use their own and everybody has a different set of standards.
This reminds me of something I've learned from a psychiatrist friend. "High-context culture" and "low-context culture" are probably familiar concepts for those into social sciences. I heard these terms from my friend only last week. These are interesting concepts and you can wiki them. According to my psychiatrist friend, one subtle difference between the two types of culture is how conservative or generous people give compliments. In typical high context cultures such as China and Japan, if a teacher is very proud of his student, he said, "not bad." In typical low context cultures such as US, when someone likes something, he may say, "I absolutely love it." There is no misinformation behind either type of expression. You just need to understand the context to know what they mean.
After my friend explained this to me, I suddenly found a lot of things became easier to understand to me. Quite a few years ago, I wrote a grant proposal. It was reviewed by 3 people and the 3 sets of feedback I received were titled "outstanding", "excellent" and "very good", respectively. And I didn't get the grant