It used to be that references only went one way--companies would call your former bosses, but you could never get a list of former employees that you could call to find out what the company is really like. Glassdoor changed all that. Now, you can easily find out what people are saying about any business.

However, while telephone references are pretty confidential and you can't know what your former boss really said about you, anyone at the company can look at their Glassdoor reviews.

As a result, you have some companies encouraging or downright pressuring employees to leave positive reviews. And, of course, you have people who are bitter leaving fake negative reviews as well. So, how can you spot which reviews are real and which are fake?

It's not a perfect science.

There's always going to be some error in figuring out what is going on. The same happens with companies that conduct reference checks for job candidates. Because you don't actually know who wrote the review, and you don't know anything about them, you can't make always make an accurate judgment about the quality of the rating. You have to do your due diligence and make your best guess. But there are a few things you can do.

A spike in reviews needs a good cause.

The Wall Street Journal reports that Guaranteed Rate CEO Victor Ciardelli, "instructed his team to enlist employees likely to post positive reviews." The result was a flood of positive reviews at the same time.

Because many people write a review after they leave a company, you'd expect a surge in reviews after a large layoff, but you would also expect them to lean to the negative side. (Although, it's perfectly possible to be laid off from a great place to work.) But a flood of positive reviews is a pretty good signal that there's a problem.

Polarized reviews.

If it's either the worst place in the world or the best place in the world, someone is not telling the truth. This is not to say, of course, that I can't love working for the same company that you hate, but if there are only extreme views, either someone probably has an ax to grind or someone is pressuring people for good reviews.

The reality is most companies are fine. Most are not the best to work for, nor are they the worst. So, be wary of companies that elicit extremes. And, as a side note, if all these reviews are correct, this indicates a company that doesn't treat people fairly. If you're one of the blessed few, you have a great time. If not? Your life will be difficult.

It sounds fake.

If it sounds too good to be true, it probably is. If many people repeat the same talking points, there might be a problem. 

Does this mean you shouldn't trust Glassdoor?

That's the same as asking "does this mean you shouldn't trust references?" The answer is you should trust, but verify. Don't eliminate a company from your list purely based on a bad Glassdoor review, but don't blindly accept a job based on good Glassdoor reviews.

Ask in the interview: "I read on Glassdoor that bonuses are fantastic. Can you tell me about your bonus program?" and also, "I read on Glassdoor that people didn't receive promised bonuses. Can you clarify what happened?"

And after you receive a job offer, ask to meet with your future teammates. Peers are more likely to be honest about the good and bad than a boss and recruiter who are trying to fill a position.

Forget the dream job.

And, most importantly, let go of the idea of a dream job. There is no such thing. So, make good and wise choices, but don't assume you can find the best thing ever by looking on Glassdoor.