talmud gemara - Source that those without a genuine need soliciting charity is a good thing

Judaism 101 says (and I have heard it many times):

Judaism acknowledges that many people who ask for charity have no genuine need. In fact, the Talmud suggests that this is a good thing: if all people who asked for charity were in genuine need, we would be subject to punishment (from G-d) for refusing anyone who asked. The existence of frauds diminishes our liability for failing to give to all who ask, because we have some legitimate basis for doubting the beggar's sincerity.

What is the source in the Talmud for this statement?

Answer

Its a gemara in Kesuvos 68a its a statement of Rav Elazar :

דאמר רבי אלעזר בואו ונחזיק טובה לרמאין שאלמלא הן היינו חוטאין [- שאנו מעלימין עין מן העניים אבל עכשיו הרמאים גורמים לנו - רש"י] בכל יום שנאמר (דברים טו, ט) וקרא עליך אל ה' והיה בך חטא

Rabbi Elazar says let's go and thank the cheaters - without them we would sin [because we hide our eyes from the poor, but now the cheaters cause us to do so - Rashi] every day, like it says: he will cry out to the Lord against you, and it will be a sin to you.