There are several disadvantages of bad audio for a transcriber to transcribe:

• Difficulty in hearing 
  Bad audio can make it difficult for a transcriber to hear what is being said, especially if the audio is low in volume or distorted. This can lead to missing important words or phrases, which can affect the accuracy of the transcript. Background noises play a big part in inferior audio recordings, such as air conditioners, people coughing and doors opening and closing.
• Increased time and effort
  Transcribing bad audio can take more time and effort than transcribing clear audio. A transcriber may need to listen to the same section multiple times to decipher what is being said, which can slow down the transcription process.
• Transcription errors:
  Bad audio can lead to errors in transcription, as the transcriber may misinterpret words or phrases. Things like talking over each other, having the microphone or recorder too far away, or bumping the microphone/recorder all adds up. This can result in a transcript that is inaccurate or incomplete, which can be problematic for clients who rely on the transcript for important purposes.
• The strain on the transcriber
  It can also put a strain on the transcriber’s ears and concentration, as they have to strain to listen and understand what is being said. This can lead to fatigue, which can affect the quality of the transcription.

Overall, bad audio can make the transcription process more difficult and time-consuming and can lead to errors and inaccuracies in the final transcript.