This should be the first thing you look at because that is what you are highering a wedding photographer for a photography experience.
Here are things you should be looking for or questions you might ask yourself during your search.
How do the images look to you?
Ultimately these are your images, and as we all know art is subjective. If you like that dark more rich look great, if you like that super bright look, also great. Choose what fits you.
Tell me how you really feel!
When you look at the images do you have any feelings? Do they spark something within you? Be honest with yourself how do they make you feel?
Does the skin of clients look fake or plastic? There is such a thing as over editing, if the photographer makes his couples skin look plastic and not realistic that might not be the photographer for you.