I agree that Harry Hoo is best. Ustinov strikes me as a kind of bad Charlie Chan impersonation. Peter Sellers is a bit over the top. Somehow Joey Foreman strikes me as just right. Maybe it's because he comes off as the smart one and Max as the dummy. Amazing!

For me, the best was actually the Bob & Ray parody from the Bob & Ray Public Radio Show of the 1980s. Some of the segments of that show have been released on CD. I wonder if this sketch is among them.

Ray Goulding is the Charlie Chan character (renamed slightly to Charlie Chu or some such).

Bob Elliot is the annoying Number One son who is repeatedly insulted by his detective father. The elaborate insults are the main point of humor in the sketch.