Damp in the bathroom and the textiles
Short answer: A bathroom without ventilation ruins towels faster than use does. Five minutes of through draught after a shower changes more than anything else.
What the damp does to the fabric
Textiles that never dry completely get bacteria and mould in the fibres. That gives the sour smell that returns as soon as the towel gets wet again, however often you wash it.
The three measures that work
Open the window or switch on the fan after every shower. Spread the towels out fully. Squeegee the water off the tiles. See bamboo towels.
If the room has no window
Leave the door open after a shower, and use lighter towels that dry faster. See Turiform and bamboo bedding.
Frequently asked questions
How long should you air the room
Five to ten minutes after each shower is enough.
Does a dehumidifier help
Yes, in a room with no window it is the most effective solution.
Can smelly towels be saved
Wash at 60 degrees with vinegar, then make sure they dry completely.