Whatever happened to Carlos from "Stuttering Parrot"?
This is an excellent question, but there is unfortunately no answer. At the epilogue of "Stuttering Parrot," Alfred Hitchcock mentions that Carlos works at the Rent-'n-Ride Auto Rental Agency and lives with the Joneses. Supposedly, he works in the Salvage Yard one day per week to earn his room and board. However, he is never mentioned again in any of the books, although Blackbeard (the mynah bird from that case) does show up again in a couple of stories.