The best way to find out about a company is to talk to former employees. You can do a search for a company name on LinkedIn (select Companies in the drop-down menu next to the search box, or click the Advanced button). Then you can look at people’s profiles and pick the ones who used to work at that company. Try to pick the ones who are closest to you in terms of degrees of connectedness.
Connect directly through the usual process by asking for introductions or by joining an industry group and then connecting that way and explain that you’re trying to get some insight into their former employer. Once you’re connected, ask some basic questions about life at the company, their areas of focus, the sorts of issues they regularly faced, and a typical day at the company.
This strategy can be a bit risky if you do it the wrong way or ask the wrong questions. Make it clear that you’re not looking for gossip or secrets, but you want to know some “day in the life” type of information. Ask the former employees things like what you can expect if you work there, what the work climate is like, and what the hot button issues are that you might be able to mention during an interview.
Don’t try to find out insider information or dig up dirt on your potential boss. Your new contact may have a long-standing friendly relationship with this person, and your nosiness can get back to the hiring manager in a few seconds.
Of course, if your contact happens to drop a little gossip about the person who might ultimately be your boss, or why they left, don’t ignore it. Everyone has a bad boss now and again, and if your information gathering reveals the person you’re trying to work for is a tyrannical ego-maniac who could reduce Genghis Khan to tears, it’s better you find out about it now than two weeks into your new job.