Wiping sweat onto the table.

I see players wiping sweat off their hands onto the surface of the table.

This practice must be legal, but surely there is a limit.

It is hard to believe it is OK to wipe any substance onto the table.

What gives with practice. 

Hi Jay,

It is a common practice and is normally allowed.  Players normally wipe their hands close to the net where the ball doesn't really bounce.