Her character is a comedic foil, like Audrey Meadows was to Jackie Gleason or Bud Abbott was to Lou Costello.
In other words, Raymond gets to be funny in situations with her because she's playing it straight most of the time. It's the actress's job and she does it extremely well.
The idea of a straight man/woman is a very important element of comedy and has been for centuries, if not millenia.
You're right, I mispoke. I should have said she's not likable.
I knew she was a conservative, and that makes her even more dislikable to me. She's just downright mean to Ray, something not in character with conservatism.