Betty (or Tawnee as she was referred to both in and outside of work since no one thought she looked like a Betty) was often described as being a spectacular beauty, able to cause the destruction of a local pub by simply smiling at one of the patrons. She was also known for a general lack of brainpower and inability to understand words with more than one syllable (one was difficult enough, thank you). It would be these two factors which led her to court the debatably human watchman.
Angua Explained to Cherry Littlebottom that Nobby was able to catch Tawnee was because she was so beautiful that she seemed completely unattainable to any man with half a brain. Not being approached however gave the girl the impression that she was unattractive, finding fault in her features and crediting why she gets such good tips at work to her dancing skills. However because Nobby is far too stupid to think he hasn't got a chance asks her out, and because Tawnee thinks that something is wrong with her jumps at the first chance she has to be in a relationship.