According to Angelo Torres, Alex Kotzky (who drew Apartment 3G) was originally asked to do Cliff Merritt Sets the Record Straight in 1964. The strip kept him too busy and he asked Al Williamson to do the job. Al, in turn, recruited Torres to collaborate. They did this job together. In 1966, Kotzky was again approached to do Cliff Merritt and the Very Candid Candidate. Kotzky again turned to Williamson, but now busy with Secret Agent Corrigan he asked Angelo to do it. Torres drew and inked the entire issue alone. Williamson did not work on the second issue... it is all Torres.
Link to the book:
Cliff Merritt Sets the Record Straight