Vinegar.
Try that first. (It also brightens colors.)
If that fails, Lysol, in the brown bottle. Kills germs.
And always use 2 laundry sacks/hampers. One for clothes, the other for towels, linens & suchlike.
After vinegar, I would try Baking Soda next.
WalMart sells it in 4 lb boxes in the laundry/cleaning supplies section. I checked it out one day and was rather surprised to see it recommended for laundry, for softer and fresher smelling clothes. I tried it with a towel that I just couldn’t get the smell out of, and it worked wonders. It recommends a full cup, but I have used it several times with about two tablespoons of Oxyclean in the oxyclean scoop and filled the rest of the way with Baking Soda.
Don’t want to run out and buy it? Pull the box of your fridge and use one third or half of that.
Edit: Just don’t use it at the same time as the Vinegar unless you want to turn your washer into a large scale replica of the elementary school ‘volcano’ experiment. 
Vinegar or ammonia are the first things I reach for if there is a funky smell left on clothes.
Definitely vinegar, but also a few drops of (pure) eucalyptus oil can turn a washful of skank into a fragrance to behold!
Eucalyptus oil smells great, acts as an antibacterial , and if enough is added, you can believe yer’ lost in a forest here in Australia.
Well, almost anyway. 
Front Loading Washer! HAH!
We have a similar problem since we got a front-loader. Water and assorted debris seems to collect behind the rubber door seal. I’ve taken to cleaning it out with hydrogen peroxide or a weak bleach solution. Just a quick wipe seems to do it.
It’s really bad in warm weather.
Who the hell wants to be lost in a forest in Australia?
The goddam Drop Bears would gitcha. 
If it’s a high-efficiency washer (we just got one), the directions say to use a little cleaning tablet every month to prevent smells (I’m at work, and don’t remember the name: Affresh? something like that). Since the high-efficiency washers don’t use as much water, apparently stank builds up.