Not only can bad smells come from the washing machine drum, they can also accumulate in the rubber door seal. The door seal is constantly exposed to moisture which means that there is a high risk for mold to develop in the fold if it is not cleaned on a regular basis. This mold, and the bad smells it produces, are then transferred to the clothes during a wash cycle. Additionally, odour- causing residues from laundry soils, detergents and water hardness minerals can appear in the door seal which also contribute to the development of bad smells.
The misconception is that the rubber door seal is cleaned thoroughly during every wash cycle, and that therefore an additional manual clean of the door seal is not necessary. However, it is during the periods where the washing machine is not being used that mold begins to develop and which results in bad smells. This can easily be prevented. All you need to do is to simply wipe around the door seal, both inside and out, with a damp and clean cloth, then run a maintenance wash as usual.