In Malcolm Gladwell's 'Blink' we're exposed to the concept of "rapid cognition," which describes how people often make very accurate, snap decisions based on very little input. This is a concept known as "thin slicing."
Of course, I was curious so I've been reading up on the subject. I discovered that this phenomenon has been the subject of a number of 'thin slicing' studies in which subjects are exposed to tiny snippets of information and measured on how accurate their snap judgements were. It seems that, in many cases, our rapid cognition works remarkably well.
In the article "Thin slices of life," Lea Winerman describes a 1993 study at Tufts University in which researchers videotaped 13 graduate teaching fellows as they taught class. They then took 3 random 6-second clips of each teacher, and combined them into one 18-second silent video clip. They showed the 18-second clip to students who did not know the teachers, and asked them to rate them on 13 different variables (such as "accepting," "active," "competent," etc.)
These scores were then compared to the end-of-semester ratings on the same 13 factors from the teachers' actual students. The researchers were shocked at how accurate the test subjects were at predicting how good the teachers would be, based on these small, random video clips.
This is interesting data, and indicates that you should really listen to your gut. However, this is an area where I think the principle of "trust, but verify" applies.
Consider this: I also read another study in which a bunch of hiring managers were asked to select the best candidates for positions based on standard interviewing techniques. The applicants were also put through structured testing to evaluate their "fit" based on a number of criteria. Some applicants were hired based on test scores, and some were hired based on the managers' traditional hiring tecniques.
The hiring managers were all experienced, and all thought they could do a better job than some structured test in selecting the right people. However, a year into the study, the group hired based on test scores was significantly outperforming the group hired using traditional interviews (as measured by job performance, team fit, results, and whether or not they were still employed by the hiring company).
In the article I read, they summarized it by saying that people often hire on "gut" but end up firing on things that may not be apparent at the gut level. These things tend to be persistent personality traits, work ethic issues, and other aspects that may not be apparent in short, structured interactions.
So, to sum it up, I believe you can trust your gut, but your gut feel may not be sufficient for some decisions. When you're making a major decision like hiring people to join your team, verify that gut feel. If structured testing is an option for you, use it. If not, spend more time checking references, use team interviewing, probe for experience and situational "stories" which might indicate issues that will surface over the long term.
Trust, but verify.