Interesting. Do the clouds in the universe include the tails of comets? Not exactly a "cloud" -- but possibly a density of 3-4 atoms per cubic inch...
The density of "clouds in the universe" would naturally vary greatly and in certain areas most probably equal the density of comet tails found in our solar system. Tails of comets are perpendicular to the orbits of planets and transition times are measured in days for planets to traverse the dust/debris fields.
A cosmic dust cloud on the other hand might be a few million miles to light years across and could envelope the entire solar system thereby destroying the bubble that protects us from the great majority of cosmic radiation.
It could also reduce the amount of sunlight reaching Earth, cause rapid decay of orbiting satellites due to friction, disrupt the orbits of a trillion+ comets and bodies in the Oort cloud and harbor numerous other bodies that could impact Earth.
I'm just a amateur space enthusiast but know enough to hope we never encounter a cosmic cloud in our life times!
:-)