They're good because they work for reasons that don't vary. For instance, if I hold a 10 lb iron ball six feet above the surface of an object with the mass of the Earth, it will fall to that surface at a constant speed every time. These are objective criteria which are very different from the subjective ones such as tastiness. It works for reasons completely unrelated to our opinions about it.
Objective? American or british pounds?
In the end it all goes back to man. There is a reality, but truth is not what you think.
Well, what is an accurate fact about reality other than a truth?