If you can easily see the holes in it, be assured that it really isn't doing much filtration at all. The same goes for exhaust filters. Apparently their multiple layers of filtration allow most of the microscopic dust and allergens which passed through the paper bag to travel right through them as well. Some even have this printed right on their filter holders. As mentioned above, dust mites are quite large compared to their minute droppings.
Pollens are quite large as well.
A cleaner with this degree of filtration may help those who suffer from Ragweed and other pollens but not those who suffer from the primary allergen found in house dust, the protein Der. Since some companies make vacuum cleaners with outstanding filtration, others try to appear just as good or superior by using these misleading phrases. Some other forms of misleading phrases revolve around how filtration is represented. Some companies will simply state a filtration efficiency percent without stating the size of the particle being measured. Summary High filtration efficiencies are very important to all of us, especially those who suffer from dust related sensitivities.