Depends how you determined someone is a good person.
If you abide by social ethics then you are indeed a 'good person' in any right, but that's not how society see's this. To be a truly good person you need to abide by all and any moral aspects from all people to be a 'good person' in anyone's eyes.
For example some cultures may maintain the morality that if you are the one to slaughter the cow, you are a good person; to others that will make you a bad person.
But if you are asking 'do you think you're a good person, to yourself' then everyone surely will say yes (that is if they are living by their own morales (which I would think everyone does)) but that doesn't mean they are 'good' as they may even be breaking social ethics. A murderer may be living by their morals which tell them never to get caught but then breaking the social ethics of not murdering; but in their mind, they're a good person (I'm talking about serial killers, etc).
That's my view on this non-existing group of people called a 'good' person; no one is good.....100%..
/Johnathan