A few thoughts.<p>I don't know specifically about Glassdoor but review sites in general tend to have either fairly positive or fairly negative reviews. I think partly people with a middling view of the product, service, employer whatever don't care enough to post a review.<p>In general, I think all or mostly negative reviews is at least a yellow flag.<p>In my experience, it is difficult, generally impossible, to detect interpersonal problems, flakiness, even extremely negative working environments in a job interview. Sometimes it comes out, but most people can put on a good face for a few hours. This is really both ways; it is also hard to evaluate job candidates as well as employers in a standard job interview process.<p>One option is "try and buy", where you work for the potential employer on a project for a few weeks to a few months on a contract basis with the understanding that either or both of you many decide not to go further. It appears hard for an employer to hide serious problem for more than a few days. A few days, however, is probably not long enough to detect a serious mismatch.<p>If it is this Rocket Fuel <a href="http://rocketfuel.com/" rel="nofollow">http://rocketfuel.com/</a>, be especially cautious of AI (or equivalent buzzwords such as "machine learning") companies. AI seems particularly prone to questionable claims, flaky people, wishful thinking and even outright fraud.<p>If you have not, try to find out exactly what they are hiring you to do and on what time scale. Are they expecting an AI breakthrough in 1 quarter? I have encountered extremely optimistic plans like this; it almost never works out.