Indeed, it's more like observing a magnetic field by dropping iron dust on a sheet of paper, and gently hit/shake it until the field lines "appear".

It makes me wonder why we can't observe dark matter (which seems to emit only pure gravitation, and no light nor electromagnetic radiation). Could it be because there's no actual matter (i.e pure gravitational waves, like the magnet+iron+paper experiment)? Or are they massive clouds overloaded with Higgs bosons?