Audio Friends Don't Let Audio Friends ...

Jsmith-

If you are invited to listen to someone's system and finish the 1st song

I feel like the host is waiting for some sort of an expression

of your impressions. Maybe they aren't but I always am. 

So regardless of whether they ask  or not the dilemma still exists.

In the end your suggestion is to follow Bambi's mother's proclamation 

that "If you can't say anything nice, don't say anything at all". 

Still makes for an awkward moment for me.

This is not about truth or lies this is about your opinion and it would not be inappropriate to state that it sounds different to your ears. We bought a tube integrated amp and a knowledgeable audiophile suggested that we upgrade the tubes, so after spending $500 on upgraded tubes we were disappointed in the new sound. We called the tube store and they said it would take 80-100 hours for the tubes to break in and now that they are seasoned the change was more then worth the wait. . Maybe the new components just need  break-in time. FWIW!

@chorus 

I don't make that assumption. But I  suppose it depends on the person. I had one audiophile friend who was excited by the music with the equipment being a hobby. I had another who seemed like his equipment was his focus and the music was a hobby. The latter always seemed to be waiting for my opinion. Which unprovoked was usually a "Sounds good", which was never a lie. But if he asked which I preferred, which wasn't often, I'd tell him.

Personally, I don't care what someone else thinks of my system, so I don't ask or expect an opinion. I didn't buy it for them.

what would you wish for yourself ?

Real friends tell it how it is.

You can roll a cat turd in sugar and tell me tastes great I am going to tell you it tastes like cat crap.

If it walks like a duck.