Earlier quoted context omitted.
I think you have some great feedback here but for me it also highlights how subjective search results can be for individuals - for example, these false positives that you mention (b2, b3) appear as the top result on Google for me for that query. It makes me think there must be some fairly large segment of the population that want that domain returned as a result for their query, no?
I would not deny that a large part of subjectivity is involved. This is why I used several markers of subjectivity in my evaluation ("what I can see", "that leaves me", "they seem to me", "I would say", etc.). And related to that: I also agree with other responses that a search often needs to be refined. So my four examples where in no way an exhaustive evaluation, but an explorative experiment, where I just used two…
Subjectively felt the gigablast results were a relative delight.