I would be surprised at myself if I liked everything. Seeing a few that I don't like, and then a few I do, helps me to understand what I am drawn to in a quilt, and helps me to learn to reproduce those elements in my own projects.
Also, sometimes it makes me more confident about my own (modest) ability when I see a project someone else is proud of and other people say is nice and I think "well- it is not bowling me over that much and furthermore I could do as well myself!"
The only time I ever feel bad about not liking somehting is if someone has gone to a lot of trouble to make it for me. The I would lie and say I love it. Otherwise, I avoid commenting, or try to say something positive which is not a lie- there is usually something I like, even if the overall look does not appeal to me.