Despite what you believe, your perception of reality does not grant the privilege of deciding what is evidence and what isn't if it fails to fit your theory. You simply cannot call everyone that disagrees with you either a liar or fraud, while praising work that supports your theory. Visit a university sometime and see how the scientific method actually works. Observation and data must precede interpretation, always.
The tennis ball analogy is the closest thing I can give you that explains how we detect the composition of other materials... in that scenario, the tennis ball is a photon, and the wall is some compound we want to examine.
For example, the reason that most grass appears green is because the chlorophyll which makes up most of the non-transparent tissues are all green too. By something having color and being seen, it must reflect something back that our eyes can percieve (visible electromagnetic spectrum!). So, that green grass absorbs pretty much every visible wavelength except green, so it bounces back and we see it. When less light is available to bounce, the shade appears darker etc. We can extend this well beyond the visible spectrum, for example, back to Io, using the infrared spectrum is generally more helpful when making determinations. Point of all this is, since the sun shoots light onto the moon and is reflected back to us, we can analyse the specific wavelength of the absorbed radiation. The more wavelengths you shoot at an object or have reflected, the better idea you get for what is absorbed and what isn't. You could argue that the moon is it's own independent light source, but in that case it would emit blackbody radiation... which it doesn't. If it was a spotlight like the sun, it would also emit all wavelengths -- but it doesnt, the moon shoots back the EXACT same light as a sample of basalt or gabbro would if you reflected the sun's radiation at it. Those giant blobs of black stuff you see on the moon.. those are massive flood basalts from what was once a molten ball of mafic rock. The grayer stuff, is the exact same thing but with slightly less iron and magnesium in the rock.
If you want to really understand the procedures and workings behind it, by all means, visit an academic library. There are entire books devoted to the many, many methods we use to ascertain chemical compositions and the physics behind the electromagnetic spectrum (EMS).
As to your last point, each of the planets has a very unique surface composition. The terrestial planets are similiar generally, but they each have unique chemistries independent of the other when you start analyzing chemistry and atmospheric properties. The moon is not merely similar to earth's rocks, it is an exact copy of the stuff found in our lava samples where oceanic crust is found. No other planet comes close to the ratios of elements and mineral content.