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?
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.