Maybe they are a thicker material, so take longer to dry. If they are folded too long before they are hung out or tumble dried, maybe this makes them smell.
I am not sure why they are having that problem - are the darker ones pants/bottoms and the lighter ones shirts/tops by any chance? If so it could be caused by different parts of the body. If you put liquid Downy fabric softener in the water with them, it will take away the smell. You can also use Arm & Hammer Baking Soda and even a little bit of Lysol - not the cleaner - the kind in the dark brown bottle.
Thanks for your ideas. To respond to some of them . . .
- it is more likely to happen to thicker fabrics
- it makes no difference whether they are tops or bottoms
- I use fabric softener in all the washes
- I have tried only half filling the drum but they still pong.
Shivvy - I just fill the washer with water first - let it start agitating pour in the Arm & Hammer Baking Soda and let it go for a minute - stop the machine and put in all the clothes and start it back up. I do the same thing when I use the Lysol disinfectant (the kind in the small dark brown bottle that has the medicinal smell). Hope one of these things works for you.
Sorry Shivvy - I just now saw your question. I have a Maytag Heavy Duty one - it is a good one but not unique in any way - just one of many we have here in the USA - but I let my washing machine fill all the way up - put in the baking soda or the Lysol and let it wash for a minute or two and then pull the knob back out so it stops completely - and put my clothes in it - push the knob back in to start it back up and let them wash as usual.