Humans seek order in chaos. When we look at something, the automatic response is to search for something familiar. So, we often see things in clouds, stains,wood grain, burnt toast etc.

good imagination, i can make faces out in the dark,in clouds, anything really! its just seeing what you want to see

The human brain always looks for patterns when presented by something seemingly chaotic. It simply pairs off what you're looking at with something you're familiar with. Same reason for seeing cloud animals!

It is very important to us to be able to recognize faces. It is more important to our survival to recognize faces whenever they are present, than to recognize that similar patterns are not faces, so we have evolved to see faces in the clouds and elsewhere. I once saw a cloud in the unmistakeable profile of Voltaire. To understand the world we make patterns; sometimes the patterns are meaningful, but sometimes they aren't. All cultures make patterns with the stars, but every culture makes different patterns, this suggests that the patterns are illusory. Another fact that predisposes us to see patterns where there aren't any is that most of us have learnt to interpret pictures, something that is so fundamental to our daily lives that we forget the neurological effort it takes to interpret a photograph as a three-dimensional scene. The fact that we can see faces in photographs rather than just patches of colour on a two-dimensional surface is evidence of our ability to make patterns; and random patches of colour, will, from time to time coincide more or less with the patches of colour we interpret as the face of a person in a photograph, so we will see a face.