The main reason behind the unpleasant odor from front load washers is mold and mildew infestation and organic decay.
The reason why front load washers are more prone to such mold and mildew infestations than other washers is the design. Front load washes contain extra air-tight rubber gaskets lining the front door, designed to prevent water leakage. These gaskets contain enough spaces to host mold and mildew infestation when water accumulates in them. However, not all front load washer models come with this design feature. This occurs because the water has no way to escape from the gaskets.
Organic decay is yet another reason for the unpleasant smell, which can worsen matters when paired with mold infestation. The organic compounds in detergents and oils stick to the wall of the washer and the plumbing provide a foundation for the growth of mold and mildew. The fiber of the clothing and substances contained in stains on the clothes also contribute to the organic material producing the foul odor.
Various techniques are applied as remedies to the problem. The simplest is the use of hot water for washing the clothes, which can effectively reduce the odor. The front loader door should be kept open for a while after every wash.
Another very simple technique is to avoid using a lot of detergent for washing. Usually front loader washers are very efficient and energy saving and do not require a lot of detergent. Using excessive quantities of detergent could result in the depositing of residue, which could worsen the odor problem.
A simple remedy is to make a solution of equal parts of water and vinegar which should be applied to the machine by scrubbing with the help of a cloth or a toothbrush. Molds and residue should be completely scrubbed off in order to get rid of the odor.