Really
Aluminum is generally not considered dishwasher safe. It reacts with the alkalinity of home dishwasher detergent (these are alkaline to remove fat/oil.) There's a thin native oxide on bare aluminum, but it's not thick enough to be a protective layer.
Many things can cause a dishwasher to perform poorly, but the cause is likely a widespread recent change in the formulation of dishwasher detergents. If your detergent was manufactured before July 1, 2010, it may have contained more than 0.5% phosphate (so-called "high-phosphate"). If manufactured after that date, the detergent probably contains no more than 0.5% phosphate (so-called "low-phosphate"). Unfortunately, high-phosphate detergents are the only formulation that reliably produces "shiny clean" dishes when used with hard water (8-grain or higher). 8-grain hardness requires a detergent that contains at least 5% phosphate -- ten times the concentration of the low-phosphate formulation -- to work well.
Try the steam cleaner next time
If your that worried