Dbl sink, with disposal and dishwasher attached. We're getting a rotten smell that lingers in the dishwasher... what so I do?

Could be several things but we need to do a bit of testing to whittle the list down. Things could be rotting in the sump area of the washer or it could be the hot water itself. Hydrogen sulfide gas can be produced in the hot water heater so lets start with that. Using the same faucet fill two buckets half full of water, one all hot and the other all cold. Drape a towel over your head in a tentlike fashion and lower your face into each bucket, smell the water several times. Does eoither or both smell like rotten egg? Rotten Egg Odor (http://www.uldrinkwell.com/drinkwell/rotten_egg_smell.html)