When we should use binning to redure noise? or How we find out we have noise?
You can plot your datapoints and see if there are many outliers to the dataset. Making frequncy plots and heatmaps helps a lot in this case.Binning helps to remove smaller erroneous data points. There are other methods of reducing noise in a dataset like applying IQR. 

If you want to reduce noise, apply Inter Quartile Range after applying binning only if you have a large dataset. : https://www.wikihow.com/Find-the-IQR