From what I understand, and I could be wrong, is that all three restaurateurs were paying into the RDA and those funds were being siphoned off by Paul Gerard as bribes so he don't make any critical critiques of their restaurants and cause them to loose business. I think that the others feigning ignorance while being questioned by Columbo was them trying to not admit to the scheme. Which don't make sense since they were victims of Gerard's extortion scheme and if they fessed up to it, it would have given Columbo a clear motive.

I agree with Brett’s bribery/extortion assessment: The payments to the RDA were in return for public praise from Gerard’s columns, et al, and also to prevent any bad reviews, whether justified or not. The RDA had both a checking and a savings account, and Gerard put the bulk of the funds in the savings account. He could then withdraw the money by using a phony ID from his secretary, leaving no paper trail back to him.

I would think that after a while the restaurant owners would realize that the benefits of the bribery portion had reached maximum value which left only the extortion part. By then all RDA members were well-established, high quality restaurants with solid customer bases. They should therefore be able to withstand Gerard’s attacks. I would refuse if I were Vittorio also.

I think if Vittorio bowed out quietly, or better yet, got his colleagues together, they could have worked something out. But that would have made a lousy episode. Also, the other members did refuse to tell Columbo about the scheme so maybe they felt they still needed Gerard.