Gold is twice as dense as lead, but to the simple minded, "they are both heavy" so they have no idea that tungsten is actually very close to gold as far as weight goes. If you know how much water is displaced by a certain weight, which is calledspecific gravity gold plated tungsten appears to be real.
Wheras if you were able to gold plate lead you could tell at a glance it was fake because it would be the wrong size.