This is something I hear people say all the time. So-and-so is a good Catholic because..., or they are not a good Catholic because... Certainly, I do not claim to be innocent of having thought this at times. What makes someone a good
Catholic? I emphasise that, as a good
Christian is (arguably?) a different topic. I believe it would be possible to be a good Christian while being a terrible Catholic. Jesus was Jewish after all

Personally, I consider regular attendance and involvement in the mass to be important. I cannot understand people who consider themselves Catholic, yet
never attend mass, or even those who only attend once or twice a year. I do not believe merely being there in body, yet not in spirt, has any value either. If you do not involve yourself in the mass (in whatever way `involve' means to the individual), then I feel you were not really there. We are all individuals, so I acknowledge and respect that different people seek different things from the mass, and are involved in their own way, but there
are those who attend merely out of a sense of obligation and are more interested in the football score than the liturgy.
Beyond that value, however, I am very undecided. I am the second generation after Vatican II, so I get very mixed messages from people around me. There are those who remember pre-Vatican II and embrace it, those who remember and reject it (or were never educated in it), those who do not remember but grew up during the changes (my parents' generation). All have very different values and tell such conflicting views on what a good Catholic is. Indeed, my personal value judgement around the mass could well be wrong too!
What makes someone a good Catholic?