She said her first appearance was as the maid 'Naomi' (https://bewitched.fandom.com/wiki/Naomi_Hogan), whom Darrin hired to help out Samantha when she was expecting Tabitha, in January, 1966. Star Elizabeth Montgomery and her husband Bill Asher were very happy with her and her performance.

Ghostley (https://bewitched.fandom.com/wiki/Alice_Ghostley) said a few months after the episode aired, actress Alice Pearce (https://greginhollywood.com/flashback-friday-chronicles-of-a-noisy-neighbor-mrs-kravitz-funniest-moments-on-bewitched-218512), who played Mrs. Kravitz (https://doyouremember.com/134311/what-happened-mrs-kravitz-from-bewitched#google_vignette), passed away (https://weeklyview.net/2014/09/18/the-curse-of-bewitched-part-2/). Asher called Ghostley that summer, when production of the new season was to begin, and asked her to take over the role (https://www.hometheaterforum.com/community/threads/bewitched-season-6.258099/) of 'Mrs. Kravitz', but she declined (https://m.facebook.com/groups/2002666590013487/posts/Remembering-the-life-of-Alice-Ghostley-for-her-Birthday/2966714566942013/). She was friendly with Pearce, and felt the role belonged to her - and nobody could possibly replace her (despite the fact that they believed she had the same mannerisms as Pearce did for the role). Sandra Gould ended up with the role (https://books.google.com/books?id=oKhGEAAAQBAJ&pg=PT310&lpg=PT310&dq=Why+Alice+Ghostley+declined+the+offer+to+play+%27Mrs.+Kravitz%27+on+%27Bewitched%27&source=bl&ots=yTuuFow2ue&sig=ACfU3U3SVfeuasCdUt6HYKLv0laSFpEB4g&hl=en&sa=X&ved=2ahUKEwi7pYC77t6GAxVtATQIHY6TDz04ChDoAXoECAIQAw).

Ghostley would later join the cast as the maid 'Esmeralda' the season after the show lost Marion Lorne as 'Aunt Clara'. She said they didn't want to replace the actress in the character (as they did with 'Mrs. Kravitz') but wanted to create a new character which was similar to 'Aunt Clara', so she accepted the offer.

Alice would have been a good Gladys.

I'm sure Sandra Gould played the role as she was told to (which was definitely different from Alice Pearce's Gladys) but I think Alice Ghostley could have done it much closer to the original.

There's something wrong with this story, it may be just a timeline thing. Ghostley was already signed to appear in a midseason replacement series titled Captain Nice that premiered at the beginning of January 67. She had a major part in that series, work would have already begun by the summer of 66. Maybe they approached her earlier in the year.

A. Ghostley also starred later on the final season of Mayberry RFD and did a wonderful job as the housekeeper. In fact, I wish Aunt Bee had left after season one of Mayberry RFD and Ghostley could have taken over for her for both seasons 2 and 3! Not that I don't like F. Bavier as Aunt Bee, but when she left Mayberry RFD after season 2, Alice Ghostley did such a great job as the housekeeper!