This problem can also be associated with dirt or grit on dishes and is pretty much the same issue in most cases.
Particles of matter, often looking like grit or sand and usually found in the bottom of the glass.
Usually the result of:
Improper loading of the glasses - item/s masked from the water spray
Glasses lying on their side
Spray arm obstructed
Too low water temperature
Food residue in the filters
Blocked spray arm
Cause & Prevention
Normally this is the result of food particles being redeposited on the items during the main wash and subsequently not being removed because the water spray does not reach the soiled areas.
It is important if this problem occurs, to check that the spray arms of your dishwasher are clear, clean and can rotate freely. It may also be an indication of a problem with the main recirculation pump in some manner. Also a "not heating" fault with your dishwasher can cause this to occur.
If the filters are not clear and clean the likelihood of this problem is greatly increased.
Rewash the affected items after eliminating the cause as above.
Always follow the manufacturers recommended dosage taking into account the water hardness.
Ensure that the spray arms are clean and that no objects are obstructing them, that they freely rotate.
Ensure that the dishwasher filters are clear.
Place tall glasses halfway between the front and back of the dishwasher basket as this exposes them to the best spray pattern.