When doing a full blown acrylic painting, I've come to term a stage the "Meh" stage (you have to do the noncommittal shrug when you say it). It's the stage in my painting where it sort of goes from a really dynamic drawing to a mediocre, blah kind of painting.
I know part of it is that I try to pull all the colors together by glazing over the entire piece in the same color. This keeps me from getting that 50 state map looks with my colors. But in doing that I usually loose all my highlights, so it looks muddy and dull. I'll add the highlights back in to make it pop and dazzle and whatnot, but it's like going through a tunnel. It's also harder to judge if I'm making a huge mistake in the "meh" stage, too.
But to get the slightly antique or soft effect, it's a road I gotta take. I just have to tell myself not to jump to any conclusions when in in that stage. Part of me just wants to "like" the painting all the way through the act of painting it, but I've come to realize that somewhere in the middle of the process I have to let it go and then hope I can bring it back.
Now at this point I could make the allegorical connection that this is a lot like life, sometime you hit the doldrums, and you gotta just get through it.... but that's a little "Chicken Soup" for me :)