Strange, but I never get an ugly maid. I always get one of those: Kaylynn, Remington, Lucy, or Genesis. Remington is quite bearable, Kaylynn and Genesis has the same face as Bella Goth, and so Lucy, but with red hair.
I have one basic law: NEVER interact with NPC working at your house (maid, gardener, bartender).
May be you make your sim to interact with the NPC, and then you are frustrated how does he/she look. I never tip them, and if they don't work well - I fire them and hire another. You never will get the same worker. Tip is considerred as an interaction too.
All I can suggest you is - ignore the NPCs working at your house, and check only if their work satisfies you. This way you won't be concentrated in their look...
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