I want to get geocode from google, and I used to do it with the V2 of the API. Google send in the json a pretty good information, the accuracy, reference here : http://code.
Well, there is the location type, which is not so bad :
location_type stores additional data about the specified location. The following values are currently supported:
"ROOFTOP" indicates that the returned result is a precise geocode for which we have location information accurate down to street address precision.
"RANGE_INTERPOLATED" indicates that the returned result reflects an approximation (usually on a road) interpolated between two precise points (such as intersections). Interpolated results are generally returned when rooftop geocodes are unavailable for a street address.
"GEOMETRIC_CENTER" indicates that the returned result is the geometric center of a result such as a polyline (for example, a street) or polygon (region)."
"APPROXIMATE" indicates that the returned result is approximate.
I test if the location_type is different of approximate, and it gives some good results.