Rabbi Yossi Rosenberg, in a Yated column (he’s a regular), mentioned a story of a girl he knows who didn’t have a husband. So she took all her money, which she had saved up for kollel, and gave it to one of these organizations. Now she has no money AND no husband, and she has been disillusioned.
Tzedakah is great. Sheker is wrong. Give them tzedakah, but ignore the fliers and “yeshuos”.