Best Of

I'd say yes, honesty is always the best policy. But there are also other considerations when it comes to right speech, whether in friendship or otherwise:

"Monks, a statement endowed with five factors is well-spoken, not ill-spoken. It is blameless & unfaulted by knowledgeable people. Which five?

"It is spoken at the right time. It is spoken in truth. It is spoken affectionately. It is spoken beneficially. It is spoken with a mind of good-will.

"A statement endowed with these five factors is well-spoken, not ill-spoken. It is blameless & unfaulted by knowledgeable people." (AN 5.198)

So we should speak the truth, but we should also know when is the right time and when we should maybe not say something because we're too angry or the other person isn't in the right mind-state to hear what we have to say. Our words should be offered with affection and in goodwill, not anger or in order to manipulate or deceive. And we should say what is beneficial to the other, not something that will harm, degrade, or confuse another.

Whether friend or foe, we should strive to develop these skills when dealing with other people, as difficult as it may be at times. And we may not always know if what we're saying checks off all 5 boxes, but we must use our discernment to judge and then reflect upon the outcomes a la MN 61.

@FleaMarket said:
I don't know if friendships can always be honest except for a rare few. Lying, cheating, and stealing appear to be woven into the fabric of human conditioning so deeply, even if one wants to be, there are layers of self-deception they've grown completely blind to through repetition.

Honesty with oneself and others is such an important characteristic on the spiritual path, it is one of the foundational stones that everything else is built on. But I think in highly evolved people often they are honest as a matter of course. If you have a few of these as friends you can count yourself lucky.

Maybe an honest friendship depends on how honest one can be with themselves, to see things as they truly are and acknowledge.

I think it naturally comes, that if you’re honest yourself you get a better understanding of who you are, and a greater acceptance of who you are. It’s a measure of personal integrity.

Simplifying according to how I understand Buddhism, a good friend speaks about the good deeds of others and says nothing of their bad deeds. While saying nothing of their own good deeds but revealing where they have been bad.

Reading the sutras on right speech can really help you see the Buddhist path to friendly communication.

Should friendships always be honest?

One should look at the middle way approach( along similar lines to what @how was saying) and take into account the impact of what you might say.... bearing in mind no two situations are the same... One person may appreciate you pointing out things, another may resent what you say or it may have a devastating effect on their mental well being ...

One size does not necessarily fit all...

On a slightly different note ( well maybe not so different-the relationship one has with oneself)

Hmm...I wonder how often we lie to ourselves in order to make ourselves feel better about ourselves...