Q. Why is the Jewish community happy to accept gifts from people whose wealth comes from dubious practices?
A. If your question implies that Judaism whitewashes unethical practices in business, this is far from the truth. The Torah warns us against having false weights and measures, putting a stumbling block before the blind, perverting truth and justice and exploiting the disadvantaged.
The Talmud says that the first question put as we seek entry into the World to Come will be, “Did you deal honestly in business?” (Shabbat 31a). It equates the punishment for unethical business practices with that for committing adultery (Y’vamot 21a). Maimonides says that a mark of a Torah scholar is that his business is conducted with integrity (Hilchot De’ot 5:13).
So if someone who is widely considered to be unethical seeks to give the community a donation or endowment, the question is whether to accept it. The decision is not easy, because there are issues of evidence of wrongdoing, of not publicly shaming a person and of not discouraging someone from coming back to the Torah and repenting. So there can be no hard and fast rule.
The ideal would be to use the occasion to influence the prospective donor to turn over a new leaf and to counter any lack of ethics in the past by going lifnim mishurat hadin – being more than ordinarily scrupulous in future. And this would imply trying to make amends to those whom they might previously have exploited. But if it comes to the crunch, it may on occasion be necessary to find a way to decline a gift or endowment, with all the consequences that may follow.