I have always believed in total honesty even if means hurting someone with the facts.
It is so easy to answer a friend's question with the answer you know they are hoping to hear. Perhaps that is why they ask you in the first place - they know you will tell them what they want to hear even if it means not being truthful with them.
During my Bell career and following that with my speaking business I have found that the truth wins no matter what so it is best to begin with the truth. You will have to go there in the end so best to get it over with especially if the truth hurts.
I lost a friend once by speaking what I believed to be the truth and something they needed to hear. In that case, the truth hurt both of us. To this day I am comfortable with my decision to speak the truth and from my heart.