If ONLY God is good (Jesus said so) then 'good' is wholly in the one that ALONE is good, yes? If such by virtue of the declaration, means we aren't 'good' thus incapable of actually valuing 'good,' we are only as good as our proximity and own image of our Creator. "Come let us reason together" the Lord says, because we have to talk to Him about what is good and what is not. If you get from God, what is good, you then can 'better' evaluate (such is the scope of all who walk with Him). God is good, simply because (it is His nature), not only can't we second-guess His motives, but we don't because we know on faith, that those motivations are pure, holy, and "good."
What then do we do, when we see something that doesn't look 'good' but believe in faith, God is nothing but good? Answer? For me, that He is good and I'll figure it out OR wait until I see Him to have Him explain it to me, if He wishes. We are talking, at this point, about something God DID do, mostly in the O.T. Our answers are both good answers (for us respectively or we wouldn't be following Him), but mine tend to be a bit given to faith where I may not always know the answer. The reason (for me) is because everytime I've had to wrestle and ask, to date, there has been a sufficient answer from His goodness. I simply assume after that, the next issue necessarily is the same: that I'll know one day or at least know I can rest in faith regarding His character.