One of Russell's objections to Meinong was that the denizens of Aussersein, i.e., beingless objects, are apt to infringe the Law of Non-Contradiction. Suppose a Meinongian subscribes to the following principle:
Unrestricted Satisfaction (US): Every definite description is such that some object satisfies it.
For any definite description we can concoct, there is a corresponding object or item, in many cases a beingless object or item. From (US) we infer that some object satisfies the definite description, 'the existent round square.' This object is existent, round, and square. So the existent round square exists, which is a contradiction. This is one Russell-type argument.
A similar argument can be made re: the golden mountain. By (US), not only is some object the golden mountain, some object is the existent golden mountain. This object is existent, golden, and a mountain. So the existent golden mountain exists, which is false, though not contradictory. This is a second Russell-type argument.
Are these arguments compelling refutations of Meinong's signature thesis? Here is one way one might try to evade the Russellian objections, a way similar to one Meinong himself treads. Make a distinction between nuclear properties and extranuclear properties. (See Terence Parsons, Nonexistent Objects, Yale UP, 1980, p. 42) Nuclear properties are those that are included in an object's Sosein (so-being, what-being, quiddity). Extranuclear properties are those that are not so included. The distinction can be made with respect to existence. There is nuclear existence and extranuclear existence. 'Existent' picks out nuclear existence while 'exists' picks out extranuclear existence.
This distinction blocks the inference from 'The existent round square is existent, round, and square' to the 'The existent round square exists.' Similarly in the golden mountain case. You will be forgiven for finding this distinction between nuclear and extranuclear existence bogus. It looks to be nothing more than an ad hoc theory-saving move.
But there may be a better Meinongian response. The Russellian arguments assume an Unrestricted Characterization Principle:
UCP: An object exemplifies each of the properties referenced in the definite description it satisfies.
From (US) we get the object, the existent golden mountain, and the object, the existent round square. But without (UCP) one cannot move to the claim that the existent golden mountain exists or to the claim that the existent round square exists.
A Meinongian can therefore defeat the Russellian arguments by substituting a restricted characterization principle for (UCP). And he can do this without distinguishing between nuclear and extranuclear existence.