Yes it is bad to drive a car or other vehicle with a bad MAF "mass air flow sensor" the mass air flow sensor is essential to a properly running engine and to keep the fuel consumption correct.
If your mass air flow sensor goes bad and you drive the car with the bad mass air flow sensor your engine may hesitate upon acceleration, stall, idle rough, stall, use more fuel etc.
So it's not a good idea to drive the car with the bad mass air flow sensor and you should get the mass air flow sensor replaced as soon as possible.
The gas savings alone would pay for the replacement of the mass air flow sensor.
The mass air flow sensor senses the air coming into the engine and tells the computer how much fuel it needs at the time which keeps the engine from running too rich etc.
If the mass air flow sensor is bad it will cause the engine to run rough, hesitate, stall, sputter, spit black exhaust smoke out and use more fuel.
If your engine is idling rough or hesitating and it's not misfiring due to an ignition coil being bad then it could be the mass air flow sensor.
If you unplug the mass air flow sensor and the engine runs better then it's the mass air flow sensor being bad and needs replaced.