Emptying the dishwasher and finding dishes with a foul (often described as "fishy") odor isn't all that uncommon. If you've never had the problem before, the logical reaction is to blame it on whatever automatic dishwashing product you're using. More often than not, though, "stinky" dishes are the by-product of a dirty dishwasher, or "hard" water.
Over time, small particles of leftover food accumulates in the filter or crevices of the machine and begin to smell. The dishwasher can transmit the odor to dishes during the drying cycle. Unless the machine is cleaned out periodically, the smell will persist.
Here's what you can do to solve the problem:
Clean the filter.
Remove the filter from the dishwasher and clean it thoroughly, using a stiff scrub brush, soap and hot water. Instructions on how to remove the dishwasher filter vary by make and model, so check the manual for your dishwasher to make sure you're removing and replacing the filter correctly. Can't locate the manual? Check online.
Clean the machine.
If the inside of the dishwasher still smells fishy after you've cleaned the filter, it's time to clean the machine. Make a simple paste of baking soda, dish soap and water and use this mixture to scrub the interior of the dishwasher, including gaskets, shelves and walls. Rinse the mixture out of the dishwasher by running an empty cycle at the hottest temperature available.
Rinse dishes before putting them in the dishwasher, or at least scrape off any large pieces of food so they won't clog the dishwasher's drainage system.
Periodically clean the filter and the inside of the machine to keep food build up from causing odors in the future.
Food debris has a better chance of becoming trapped in gaps of the machine when too little water is used during the wash cycle. Avoid using the kitchen faucet when the machine is filling with water so as not to divert water resources from the washing machine as it fills.
Check your water softener.
Make sure your salt levels are acceptable, try cycling the salt, or consider switching your water softener salt to a specific kind - iron removing salt can help with dishwasher odors.
Combine a good cleaning with some pro-active prevention and you should be able to banish dishwasher smells for good!