How does Buddhism view conscience? Do you follow your conscience or Buddhist morality? Your conscience does not always in line with Buddhist morality. For example, cakes are not poison but generally are not considered as healthy food, Buddhism does not prohibit you from selling cakes to other people. But your conscience says, it's better to sell something that can make contribution of health to people at large e.g. healthier food compare to cakes.
Do you ignore your conscience or follow it?
Although selling cake is not wrong livelihood but your conscience tells you to choose healthier contribution. It's easy to fall into extreme. Buddhism is the middle path. How do you keep it balance and not neglecting your conscience at the same time?
If selling cake is better than selling drugs, selling healthy food is better than selling cakes and so on. I am wondering what is the use of Right Livelihood as in the Noble Eightfold Path, are they all considered Right Livelihood, except drugs?
What I meant was which one do you listen to? Listening to conscience is necessary, as you said. But what you think is right or wrong does not necessarily true or middle path. If selling healthy food is better than selling cakes, logically one will follow what is best, we consciously put the latter one into the "not to do" list and choose former one as our Right Livelihood. But how do you know if you follow this kind of thinking you're not going to fall into extreme? We create our own version of Right Livelihood. Both cakes and healthy food are not considered wrong according to Buddha.