I have inspected a number of households that use the same dishcloth over and over again without laundering.  I used to do the same until my wife insisted that we launder our cloth daily.  

The porous nature of dishcloths allow for the accumulation of small particles of food thereby providing a moist, wonderful environment for bacterial growth. Bacterial counts including mold and yeast recovered from such cloths have been amazing, not to mention the smell. 

During my bachelor days, food safety and sanitation in general was somewhat questionable.  The dishcloth, rather, dishrag, would be changed when the smell became unbearable, probably not the best thing to do, kinda like guessing whether poultry is cooked without using a thermometer. 

It is simple, one could launder the cloth or place the cloth in a container of water in the microwave for a minute or so, that should do it. 

Fecal coliform bacteria, including E.coli were recovered in such numbers during the production of the television series Kitchen Crimes that were horrific — and don’t get me started on the amount of yeast and mold. I’m frightened as is.