This superstition my mother used to tell me about dishrags. She believed that whenever you dropped a dishrag, that meant that someone would come knock on your door soon. This could happen any time of the day, any time of the year, just in general someone would be there soon.
I’m not sure if this is a good or bad superstition but it seems pretty general and forward. I do not know if this ever comes true or if it means something else. If it were to mean something else I believe that it would mean that right when you are doing a lot and moving a lot and are really busy, someone will come and visit you right then. I picture a housewife moving swiftly in the kitchen and dropping her dishrag while busily cooking and being flustered when the doorbell rings right as she picks it up. So it could be a metaphor for when you’re busy something else will come along too.