Cooling fans don't help to lower ambient air temperature. As we say here - "fans cool people, not rooms"
In fact, a fan may (because of the electricity used for the motor) actually slightly heat up a room.
Cooling for a laptop is determined by the ambient air temperature. If, for instance, your room is at 30C, then the laptop can never be cooler than 30C, and then only when switched off. WHen it's running and generating heat, it will always have a higher temperature. As it's internal temperature increases, the efficiency of it's cooling increases, since the difference (gradient) of the "cool" air passing over the heat sink is lower than the temperature of the heat sink, making for more effective temperature transfer.
Also, the room and usage may determine how much and how fast dust and dirt accumulates ion the cooling ducts and thus how often you should clean it out.