It's really hard to tell sometimes. I have a walnut EB-3L and a once cherry, now faded to brown EB-4. Ignoring the telltale parts under the bridge mount, the pg and pup covers, the EB-4 looks like walnut with more luster and depth to it. But you really have too twice and squint your eyes. The EB-4 features the most red on the back of the neck (not on the body though) which I always took to indicate that the fin reacts differently on maple (neck) than on maho (body).
That specimen in the auction has the luster of a former cherry bass, but I might be mistaken.
Uwe
