Correct me if I'm wrong, but can there be such a thing as "neutral dust" in interplanetary (or inter galacting) space? Dust grains, small rocks and astroids (and atmospheres) are generally bombarded with "cosmic particle rays", i.e. mainly protons, from both the Sun's plasma along the ecliptic and the surrounding galactival environment. On the objects' side facing the Sun, there is some degree of photoelectric effect, releasing electrons. So, there will be surrounding thin layers of plasma around each object - or if they have any atmosphere, that one will be (dis)charged. The Moon has "dust fountains" due to these effects i.e. repelling dust due to the charge contrast along the day/night band.
I doubt interplanetary dust or small rocks will clump together, but rather be positioned at EM equilibrium states between them - well, they're probably even animated because of this (like plasma dynamics, but with the additional inertia of mass). Even IF these dry rocks clumped together, how would you imagine it would look like? I'd say, like a clump of dry rocks (and couldn't it then be explained by magnetic positioning and re-polatizations as they group, like a clump of small ferromagnets would?). We should also see several such states of accretion in the astroid belt, which I believe we don't. All the dust and rocks seems to be evenly distributed. Also, there is the explanation of the Saturn ring, which I'm not too familiar with yet, but I believe there is a similar case of charge and dustry plasma equilibrium (but there the planet plays a central role).