Medium Low Credit Score?

Can anyone tell me what a medium low credit score is? A few prospective tenants refuse to provide their credit score to the question contained in my LPA pre-screening questions. Instead they use words like fair, low, bad, not great, working on improving, fair/good, not sure, not so good, etc.

Since the US average FICO score is about 786 I would assume a medium low score to be sub 600. What do you think?