As far as it was explained to me the smells from decomposition, a situation referred to as PUTRESENCE arises only when there is anaerobic decomposition. 

This is caused by not enough air circulation in your worm bin.  In order to rectify this, you just find the area that is causing the smell that does not have enough air and fluff the surrounding material/news paper.  Once it becomes aerobic decomposition again, the smell and putrescent situation should stop. 

The beauty of the indoor worm bin compost which is different from outdoor compost, is that all the decomposition is done by the worms.  Other ‘decomposers’ such as flies and bacteria, are kept at bay thanks to the small contained environment.  Technically, bacteria is still doing the decomposing, but it is all contained in the digestive tracts of the Red Wiggler Worms, therefore, even more perfectly contained, keeping all smells to a minimum, while providing you with nourishing compost!