I have to admit that I don't know this person and I could just be sprouting BS but I saw
this and couldn't help thinking...shouldn't you already know this even before you accepted the job offer? The problem with taking a job just because it's offered to you, without assessing if you would actually like to work for that company (ie. work culture) means that you're going in with a 50% chance that you might hate it.
Granted, you can't know 100% that it's going to be a very good fit because it depends on 1) how good (reliable) your sources are; 2) if their perspective is coloured by specific incidents that does not translate to certain company culture (black sheep); 3) they're trying to sell you on their company, which boils down to inexperienced recruitment.
And there are cases of serendipity. People who blindly land a job or launch a career and find that it's really "the best thing" that could have happened to them.
Just in case any ex employers are reading this and you've somehow identified me (God forbid!), you guys are awesome. It's not you, it's me. Aahh..Classic. OK, I do mean this though. My ex employers have all been great folks. I also credit one of them with inadvertently steering me on to a different career path (and I mean it in a positive way).