Maytag Dish Washer

First we don't use the dish washer daily. If you don't use it for a week, we find water in the bottom of the washer. When we're done using the washer the bottom is dry. I'm doing a test now to see if maybe water is returning to the washer from the drain line. The line has been removed from the garbage disposal and a plug line installed. If this is the cause why is water retuning to the washer, and is there a check valve that may be stuck open. If this is not the issue could the water value be leaking? Why I'm thinking it's the drain is the water stinks in the bottom f the washer..

Thanks