Well, I know you’re going to think that I’m trying to avoid the question, but as far as I am concerned, there is no ‘Good’ in the Platonic sense. No ideal form to which we can refer. If you say that someone is good, then I suggest that that statement is meaningless unless we have a reference point. That is, in what respect is he good? A good father, a good driver, a good politician?
Otherwise, the term becomes all-encompassing and that isn’t possible unless I was a Christian describing God. That is, someone with no negative attributes at all. The epitome of goodness. Goodness itself.
Now unless you have someone that is identical to that (I’m assuming that you don’t), then that person has to have some attributes that are not good. Let’s face it, none of us is perfect. So you quite literally have to be specific as to why that someone can be referred to as good (she gives her time for good causes, she’s kind to animals etc). Whilst at the same time, passing over her attributes that could not be described as good (she’s racist, she lies etc).
That said, there is a sense in which we can say something like: ‘I am trying to be a good father/husband/friend’. But even in that sense, we have a personal and very specific impression of what would constitute being a good father or husband. There is no ideal Good Father. Just a lot of attributes that each of us would list as a requirement to be considered such. Most of us just try to cover as many bases as possible.