If this is not a diesel, then the engine is running too rich. The deposits that you are talking about are carbon deposits that result from too much fuel being sent into the cylinders.
Thick black smoke can be produced by a variety of things, including the burning of some kinds of plastic.
Pollution can come in many colors, depending on what the pollutant is.\ but pollution is usually referred to as a thick black or brown cloud, such as exhaust or smog.
Thick Black Theory was created in 1911.
Thick white smoke is caused when coolant gets into a cylinder and from there into the exhaust. It is a sign that if it is not fixed real soon, you will blow or burn up your engine.
Tar. Tar is a thick, black fluid that contains many cancer-causing substances but is the flavoring in cigarettes.
could be oil from valve cover gasket or not changing plugs wires
thick and black
fungi and dirt
Maybe a blown head gasket
what logo has a black squiggle and a black dot
ginnosuke from tokyo underground has thick glasses and is a dude with black hair
many toilet papers!!!