It's a good idea to read the emotions of the people around you.
One of my interviews went amazingly well. I had posted a resume on Monster, been invited the next day (Friday) to interview the next Monday. The hiring manager was lapping up my story, and after half an hour introduced me to the owner, who hired me on the spot. I was set up in a cubie the next day.
When I started circulating through the bull pen, however, I discovered that no one in the ranks was initiating conversations, and didn't particularly like hanging around if I started one. There were a couple of other big talkers in the group, but they had their hands full - I could tell their project was in serious trouble. So I progressively backed off until I could figure out what was going on.
Turns out the company was not so much a developer as it was simply a documenter - they read source code and flowcharted business rules, but didn't write anything. Much of this was done through code analysis software, so a lot of the people simply ran scripts on files, and cleaned up the generated flowcharts. Having a real programmer in their midst was a bit threatening.
The project I was engaged in was a new direction - actual development rather than simply documentation. As we hired other people to fill in, the original workforce, with a few exceptions, warmed up. Some of them got new and more interesting work as a result of the project I was working on, and I was able to bring them up to speed on salient points. Initially, I was viewed as a bull in a china shop.