Let's have an example case. How about minimum wage? The point isn't to ARGUE about the minimum wage, but to point out how different people can regard it as clearly good or clearly bad or somewhere in between.
A minimum wage is a price floor on the hourly rate you're allowed to pay someone to work. It doesn't apply in all cases (not in the case of a salary, or jury pay, or hiring a kid to mow your lawn), but it applies in most.
Obviously, some people will be inclined to regard the minimum wage as "good": those who earn at or just above the minimum wage will be inclined to be thankful that it is "impossible" for them to earn less than that amount, and might even desire for the minimum wage to be higher, so they can earn more per hour. Some will obviously be inclined to regard it as bad: employers now have to pay more per worker, so it becomes more problematic to just hire more people to get things done faster/better, and employers would be inclined to want the minimum wage to be lower.
But what about non-obvious cases? How about the unemployment rates among younger workers, especially minority workers? The Youth Unemployment Crisis Hits African-Americans Hardest : Code Switch : NPR
Is the minimum wage "good" for them? Is it better that they go without a job than get paid less than $7.25/hr? These aren't easy questions to answer, especially to answer them on a group level.
BUT, they can be answered on an individual level. Without a minimum wage, each worker would be able to decide for him/herself whether what their employer is paying is worth it. If you're just a 16-19 year old, still living with family, with no rent to pay or food to buy, would $5/hr be OK? Or $3? Each individual would have their own answer to that, with which they would be nominally satisfied.
But no, we have a minimum wage. No one, neither employers nor employees has the right to work for less than that amount.
Note here that I'm not asserting "good" or "bad" or other values. I'm asking questions. I'm posing how one might go about ascertaining what is good or bad for people. In this specific case, I -am- suggesting that the individuals involved are perhaps in a better position to decide what "minimum wage" is good enough for them.