Sugar promotes healing and prevents infections; it also cannot breed bacteria due to the high concentrations of sugar. Sugaring is also easy clean up because sugar is water-soluble. 

You can wear gloves! They are an effective barrier to both you and your client for potential communicable diseases. 

Shaving only causes the hair to be blunted by the razor which leaves the hair appearing thicker. 

Sugaring is effective on short hair as well. Therefore, more of a permanent solution is hair removal. 

Unless you eat the sugar, it will not get into your bloodstream.