My wife had a position like this once ... she phoned me at 3:30 to come pick her up.  She had applied to a technical college to do some instructing, and they told her everything was planned, she just had to modify things for herself.
The interview was brilliant, enough to get her to leave her previous position, which paid a lot more, but didn't stimulate her at all.  Benefits were great, she was working close to my office etc.
She goes into work, and the same thing as you ... she tried to be friendly, no one even responded to her hellos.  Once she finally tracked down her new boss, she was kept waiting for 45 minutes, at which point she was brusquely asked to teach the admin assistant HTML (not remotely part of her job description).  She mentioned she had a few questions, and had her head ripped off.  Everyone was totally stressed, hated the boss, etc., so it just wasn't a welcoming work environment.   To top it all off, none of her lessons were remotely planned, and her workload just flew through the roof.
She walked out, much to her happiness and mine, telling them that they totally misrepresented themselves during the interview, and that she wanted no part of that culture.  No fallout came from this in any way, and shortly thereafter, she found a perfect job for her that she loves to this day.
Don't suffer fools gladly, it will cause too many unhappy moments.  Good luck!