Why is there still dirt on my dishes after using the dishwasher?

you probably have a cheaper end dishwasher... or your water heater may not be putting out hot ehough water to wash with or try using cascade dishwashing blocks.
most cheaper washers will not do much, you put in dirty dishes, you get out HOT dirty dishes.. you might look into buying something over $500 , you wil usually get a good washer.. KITCHEN AID makes a great dishwasher for around $700

does your dishwasher have a filter on the bottom somewhere. If so check often and clean often. this means that your washers pump is not rated to handle any debris and won't be able to send down the drain any food that ends up in the washer. over time some sediment may build up and reduce the effectiveness of your cleaners. an industrial grade machine will be noisier but able to flush most food down the drain.

Do you have hard water. I never had any problems with my dishwasher until I moved to a new town that had hard water. Now it almost doesn't seem worth using it. The hard water kept the powdered detergent or the tabs from disolving, liquid detergent works better but there is still always something dirty left over.

continue rinsing. check any filters or screens you might have, look into whether you have hard water and consider getting a water softener. load your dishwasher more sparsley so that the dishes don't get in the way of each other and always check to make sure that none of the taller items get in the way of the arms spinning, we often have this problem with pans and spatulas