Most programmers know about the Joel test - 12 yes/no questions to quickly evaluate where a company stands in its development department. These questions are things like "do you use source control" and "do you have a spec".
What are the equivalent questions for sysadmins? What are the 10 or 12 yes/no questions that indicate the cluefulness of the employer?
What hours do you try to work, what hours do you normally work, what hours do you occasionally work. You can learn a lot from these answers.
The best advice is besides talking to the Employer, is to talk to the employees. While many companies are replacing them with automated phone systems, I used to be able to learn more about the company by talking to the receptionist then I did from the interview.
Also don't forget to Google the company and the company officers. A friend of mine took a job then discovered that the owner and CEO where under inditment on several federal charges. He left as soon as possible.