If the food is prepaired badly, then we will complain (under or over cooked, prepared wrong, way to much disgusting oil, etc). But if it is just we did not like it, then no we wont complain.
I will note though, so many Disney servers are so great about noticing if you dont like that. Many times we have had things removed from a bill because the CMs knew we did not like it. We have almost always been asked if the meal is almost untouched. And when mentioned it was not to our liking, more often then not, when we get the bill we notice the "offending" meal is not on it.
So to thank the CMs, or Servers in any other resturant, we will always add the price of the missing meal to our tip. Sure we dont have to, but we always apprciate good service.