A sledgehammer to the kneecaps isn't objectively any better or worse than a nice massage, but pointing that fact out is usually a quibbling issue of semantics.
I've been trying to understand this sentence for the last five minutes and am coming up blank. The objective aim of life, any life form, is to be successful; taking a sledgehammer to the kneecaps I would think to be directly contrary to your ability to do well, thus why we feel pain at all.
Define "objective," "aim," "life," "form," "successful," and "pain."
Less semantically, there's no particular reason survival, lack of damage, reproduction, etc are "objective" goals or metrics just because they're common or even theoretically ubiquitous amongst a certain class of things. There are decent arguments you can make for
assigning them into those things as a matter of convenience, ie most life wants to not be injured most of the time, so we might as well call it "bad" as though they're the same thing 100%. But like any shortcut it starts to break down when you look at it too closely or from the wrong angle.
For instance, we could just look at opposing goals. Say you have roaches in your home. You don't want them there. They want them there. Is murdering them all with insecticide objectively good or bad? Presumably it's bad for them, and you claim it's good for you but we haven't defined "successful" well enough to know if that's objectively true or not... but unless we can say it's objectively bad for you as well, we can't say the insecticide is objectively good or bad, only objectively good or bad
from a certain perspective- which is to say, subjective.
It gets worse when you start throwing in any variety whatsoever in the individuals in question, because then you lose even that. Maybe some people likes roaches! Maybe some roaches don't want to live any more! Now you can't even say they're objective from given angles, or rather, you have to acknowledge their "objective" angles are even narrower than you thought.
All of which boils down to my original point that
nothing is objective, but some things are safer than others to call objective as a matter of expediency. Sledgehammer to your kneecaps will be bad the vast majority of the time, hard drugs will be bad most of the time, differing career qualities will be totally subjective, chocolate will be good most of the time assuming you're human and not watching your weight/teeth, so on and so forth. None of it's objective, but some of it lends itself to being called as much better than others, especially in the right context.
I will agree that quality is always a contextual comparison, there is no universal blanket you can use to judge all cases in a vacuum. But I steadfast do not believe that all concepts of quality are just a whim of the mind and according to the person as they feel fit. My doodling from kindergarten are not better than my drawings now, and anyone who would consider them such is a person who does not actually understand the process of visual art and can't be considered an authority to judge it.
Good example of the above in action. "Everyone would agree on this, and if they don't they're unqualified to judge it in the same manner that everyone else is." Which is basically just a tautological assertion that your current drawings are better than your former drawings, by the metrics of the group you'd consider relevant to judging this particular scenario.
Meaning subjectively unanimous in such a way that you feel confident calling it objective without too many issues. It's a useful designation, but it gets dangerous when you start forgetting that it's a designation, not an inherent facet of reality.