Update: You can also construct a Map Service query and paste the resulting URL/Query String into a network link if you wish to pull a sub-set of the map services layer(s) into Google Earth. Create a query with the output as HTML (this also ensures that the query parameters have been set correctly). Copy the resulting URL from the address box, and paste as a network link. Change the f=html text to f=kmz. For the "Return fields", always use * as the wildcard to have all fields brought over.
Caveat: I am doing this to, whenever possible, minimize the number of layers via definition queries for selected map services. I get good results on one set of "queried network links" against a map service, whereby the popup information box configuration set up in the originating map document carries over. Unfortunately, when trying this with another map service, the Popup box configuration does NOT carry over (it defaults to a generic table) despite (1) having the wildcard for returned fields and (2) the resultant query results' records displaying the correct popup configuration via the REST interface.
Edit: You will need to have ALL fields exposed (even those not used) for all features within the source Map Document or else the popup will not work properly.