The rubber door boot on a front-loader is a gutter. Hair, coins, and leftover suds sit in the folds. Close the door after every load and you grow a biology experiment. Top-loaders have their own version in the lid area and dispenser, but the boot is the usual complaint.
Use HE detergent and less of it than the cap suggests if you wash in cold water with small loads. Extra soap does not get clothes cleaner; it stays in the machine.
The gasket is a water trap
After a load, wipe the boot dry, including the hidden fold at the bottom. Leave the door and dispenser cracked until the next day. That single habit prevents more odor calls than any tablet.
Detergent math and the clean cycle
Run the tub-clean or steam-clean cycle the manual describes, with the product it names. Do not mix random bleach, vinegar, and tablets in the same afternoon. If the boot is already stained and slimy, cleaning helps; a torn boot that leaks is a different repair.
When freshness is not the issue
A growl that rises with spin, a leak onto the floor, or a door that will not lock is not solved with leaving the door open. Stop using a leaking washer. Odor plus a failed drain is two problems; clean the accessible filter if your model has one, then book drain diagnosis if water still sits in the tub.
