We temporarily removed our dishwasher, but the water in the tubing stinks and spills out every once in awhile. I secured it with a string so it is suspended and covered the end with foil. It worked for awhile, but it leaking again.

Go to the hardware store in the plumbing section get a abs 1 1/2 inch Wye by dishwasher fitting (the capped ones) insert it in to the end of the dishwasher hose where it is stored, and use a hose clamp to seal it shut.

I would also consider elevating the dishwasher and trying to just drain as much water out of the dishwasher hose as you can.

There is only a limited amount of water in the sump area of a washer, the leak should stop if you lower the drain line to the floor and allow it to drain onto a towel. A simple cork should stop any air circulation so the smell should end too.