Purdy is correct about trapping moisture but expounding on temperatures of compressed air, many of us use solvents that are temperature dependent. For example we use a DT 860, 870, an 885, and 890 reducer which the last two digits reflect the temperature. Air storage in the tank allows the air to cool. Also, heat is generated by compression, which is a by-product of two-stage compression. If the compressor is running at capacity, the air has no time to cool, and can even be as much as 10 degrees hotter than air that has had time to cool in the tank. That is why many of the high-end guns have temp gauges to measure the air temps of the air flowing thru the gun. Temps affect solvents, how the paint is atomized when sprayed, and on some colors even slightly alter the tint. This even can cause problems when between coats (flash times) when the compressor catches up and the air cools off. Then the paint sprays differently at the beginning and end of each coat when the compressor is too small for the gun. Again, this is WAY more info than what many want to know so I guess it boils down to the quality level you are desiring.