I try to say something positive, especially if it is done. ie. I like the colors, pattern, fabric -something.
Here is what was said about one of my first quits.
My sister, "Why would you make something so ugly." She is very honest in her opinions. I think she didn't like the colors.
My brother, "Wow, what a great looking quilt."
I gave it to someone who lost everything in a fire. All 6 of her kids wanted the quilt. They loved it.
I took one to show and tell that I didn't like. The ladies in the back of the room said it was beautiful.
So who knows.
If a quilt isn't finished and they want constructive advice I'll give some suggestions.
I have a friend that we feed off each other. We have helped each other make better quilts.