Dishwasher problems?

I previously posted a question about this subject and have tried every single tip kindly posted back to me. I've checked the dishwasher inside out, its spotlessly clean, I ran various commercial cleaners through it inc soda crystals. I check how all the plates and dishes are placed making sure nothing is... show more I previously posted a question about this subject and have tried every single tip kindly posted back to me. I've checked the dishwasher inside out, its spotlessly clean, I ran various commercial cleaners through it inc soda crystals. I check how all the plates and dishes are placed making sure nothing is blocking the spray arms but still, the majority of any cups or dishes placed on the top shelf still have what appears to be a residue of sand inside them after the wash has finished. I also rinse everything before hand and use the rinse feature on the washer before using the hottest setting. I also use dishwasher salt and rinse aid.
Anyone have any idea why my stuff on the top shelf still comes out dirty and what is this sandy stuff because I'm at a complete loss?
Thanks.
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