Why it is good to be honest?

Answer 1

It is good to be honest, but it is not realistic to expect others to be honest at all times. This presents a difficult contradiction, but according to the definitions of 'good' and 'honest,' the two don't have essentially similar connection between them. I mean, it's 'good' to be 'good' in any possible way- its pretty much what must be real.
I don't know, maybe it's just my opinion. but everyone inherently knows that it's good to be honest.

Answer 2

because you should convey what you really think.

This means the people you meet will have the correct and honest impression of you whether they like it or not, it means you wont have to worry about keeping up all the lies you've told people for whatever reason, it also means that people will rely on you for a proper opinion and one that isn't sugar coated, people will be more likely to trust you with many different things and being honest helps you learn to be as fully satisfied with yourself as you can be.

but most importantly being honest about things makes you a lot happier in general.