Most manufacturers advise changing vacuum cleaner bags often in order to ensure the best vacuum suction.  Compromised suction can result in leaving much of the dirt behind when vacuuming and it can also lead to clogging.  In addition, with some vacuum configurations, vacuuming with a full bag does not allow for effective airflow around the motor (this airflow is often used to cool the motor) and could cause overheating or other problems.  In some instances using vacuum bags not recommended by the vacuum manufacturer may affect one's warranty - it is worth checking into this before making a purchase.

Up-to-the-minute deals on vacuum cleaner bags can be found below: