In the local community. Find out who is buying from this company. It can be other companies. It can be people in the local community. Call these customers.
Customers can reveal volumes about a company's ethics, reputation and standing.
Also, a company's competition can give you some useful information. Then there are the company's suppliers. These people can tell you much about how operations are managed. For example, they can tell you if the company pays its bills on time. Depending on the type of business, you can go to the place of work and have a look around for yourself.