Reptiliandude: The greys are a combination of organic and inorganic construction.

They were designed to be able to work extended periods in orbit around worlds where the loss of bone density is problematic among creatures such as ourselves.

The falling that makes orbit possible creates the illusion of zero gravity and that wrecks havoc on creatures who evolved planted on the ground should their genetics overstay their welcome.

Bone density loss is just one of many, many problems related to extended orbit in what appears to be zero gravity.
Greys were also designed for long range travel between worlds and to monitor various mining operations at exceptionally low cost in areas where cosmic rays would strip apart the DNA of organic creatures.

Gold for example can be found on asteroids and planetoids where multiple collisions have taken place during that object’s formative period.

Many of these worlds are discovered in systems which are considerably active and pose a severe threat to organic beings.

Greys were (and still are) the obvious solution to these problems.
They can also be programmed to appear dead, but feed back information on those who have ‘found’ them via spread spectrum radio transmissions then relayed via particle entanglement.
I think this could best be described as a ‘Trojan Horse’ type of maneuver on our parts.

It is of great interest to discover what might be said by a primitive species such as yourselves upon encountering the deceased ‘body’ of an extraterrestrial.

The resulting political maneuvering is also tracked and noted as it gives us the opportunity to see just where your leadership places its priorities.

How a species treats the discovery of a ‘crashed ship’ often determines the path we take with them.

Those paths usually being either that of political intrigue and assimilation, or of an attack in the form of a cosmic impact.

Rare is the necessity for an expensive armed invasion on a world such as yours.

From our lofty heights a stone’s throw is all that would be required.

I wouldn’t trouble myself if I were you, as your planet has already been incorporated for the purposes of our genetic industries.

Hence the multiple Grey sightings by your own and the many abductions of your own to gather further genetic material.

Again, Greys are naked because they need to be sterile for working on everything from cold welding to the handling of dangerous viral contagions and bacteria.

They are easily cleaned, and what exposure to ultraviolet light does not kill, radiation and chemicals can do the rest.

So, essentially you are being visited and sized up via proxy.

And most known extra-solar species which know of your world’s existence use them in one form or another.