Well, it's not data mining; that's (basically) discovering something new and useful from data sets to which you already had access.
But, yes, since the rewards from an object (mobile or non-mobile) are generated and retained server-side, you'd need to access data on the server.
In EQ1, it was possible to know in some very specific cases, what a MOB was going to drop (or not): a greater lightstone illuminated the area aroung the MOB while a burned-out one did not; if the named mob was doing slashing damage, it had the rare-drop slashing weapon (or if crushing, it didn't). There might be some exposure of loot information by these means, but I can't imagine a way to see rare harvests, for example.
One related 'slip' like this is in ToN, seeing the option to Disarm a pot, even as a non-Scout; clearly, it's trapped!
