Ask HN: Legal to access data on purchased used NAS?

Hypothetical question here. Generally, is it legal to access/use information found on a used storage device that you have purchased?

Specifically, suppose company A is a competitor of company B. Company B goes out of business and has an auction to sell off its assets. Company A purchases used Network Attached Storage devices from auction. The NAS is not reformatted, and contains various data from Company B. What information, if any, is legally fair game for company A to access, and or use?

I would assume information regarding account info like account numbers, login credentials, etc would not be legal to use (IE it would be fraudulent). But what about information like product information (SKU / product interchange relations), pricing matrices, etc.

Perhaps none of it is legally fair game? I don't know. Please provide input regarding this hypothetical situation.