As a person with dirty cloth does not hesitate to sit anywhere, a person whose character is spoiled, will not hesitate to do bad. Every one must have experienced this ( the first half I mean :-) ) particularly in rainy days, when you come out of your home, you will take all care to protect yourself from the mud etc. But once somebody splashes some of it on you, you are tension free. you will not be bothered by the mud there after. Similarly to save your character, you have to take care only at first time.
Parmeshwar (God) doesn't himself take a 'danda' (Stick) in his hand to protect someone. But he gives the 'buddhi' (Intelligence) to a person whose safety he wishes, to withstand any attack ! One can recall many instances in the life of Shivaji Maharaj where the above subAshita can be perfectly applied!
A person, who wants to get some work done from another person, praises him till the work is pending. (after the work is done, he doesn't need that person. As,) once you cross a river, why will you need a boat? This Subhashitam describes, how selfish we are when dealing with others. Obviously not to be practiced.