I agree with you, the whole thing is flawed when it could be better. When you ask the question "is my blue your blue?", you are evoking the old philosophical question, and it's a question about color perception, not words. This test did not test color perception, it tested "what word do you use?"
I think of blue as a pure color, and green as a wide range of colors all the way to yellow, to me another pure color. so if there's any green at all in it, I'm going to call it green. (maybe it's left over from kindergarten blending "primary colors". also, while I like green grass, I don't like green as a color, so any green I see is a likely to make me think, ew, green) But in terms of what I see, I can only assume I'm seeing the same thing as everybody else is because the test is not testing it. Just because I call something green doesn't mean I don't see all the blue in it.
>Edit: Possible improvements: changing the wording to "this is MORE green" and "this is MORE blue" and randomizing the order in which they are shown, somehow. I realize you're just doing some kind of binary search, narrowing the color range.
yes, the test should show you pure blue, then a turquoise mix, then pure green, and a ... etc. It should also retest you on things you already answered to measure where you are consistent.