I still don't think this will work for a few reasons. A lot of pond building experiences are arbitrary. If for example, a dirt guy comes in over bid, because he said found a vein of sand through your clay, are you happy he caught it, and pay the extra money, or do you feel like he should have factored that in. Did the owner get a core sample prior to starting? Did he have a clear defined contract? Was the owner aware of any watershed issues?
Online reviews like Angie's List, at least to me, are suspect unless there is a volume of responses. If you go to Amazon looking for a widget. If there is one great review do you buy that widget? I don't. I would be inclined to buy something that had 100 responses, and 2 of them were awful. At least the data set should be less skewed.
I think a new pond owner posting pics of his project, maybe relaying who built his pond without it being a sales ad, then PMing others if they ask, is the way to go.
In my particular example, I have far to much shallow water so the surface area fluctuates greatly throughout the year. Is that my fault, or the builder's? I think it's mine. He did exactly as I asked, but didn't offer any suggestions to keep this from happening. So am I happy with him, or disgruntled? It depends on the person writing the check.
Researching projects here on the forums, visiting several past projects of a dirt guy, and having a clear set of goals is the way to go to me.