As a fellow recruiter/manager, how much do you count your gut instinct into the hiring decision? If someone on paper has all the experience you want and answers all the technical questions correctly and the hiring manager loves him, but he just for some reason gives you a creepy vibe or is a little off-putting -- I'm sure you have been through that before -- do you make a call based on that? Do you share that gut instinct with the hiring manager?
I'm sure this will be a controversial answer, but I put a lot of stock in my gut -- if what it's telling me is negative. Every time I've ignored a negative gut instinct in hiring, I have ended up regretting it. Every single time.
Now, there are two important qualifiers I'd add to this:
1. I pay attention to my gut when it's saying "don't hire." But I try to ignore my gut when it's saying "hire." I want my decisions to hire to be based 100% on solid, real-world evidence -- track records of success and so forth. If I'm going to make a hiring mistake, I would much rather it be that I mistakenly pass up someone good than that I hire someone bad.
(And I've found that positive gut reactions are more likely to be wrong. They're often based on things that really shouldn't matter in hiring -- such as that the candidate feels like your type of person, or that she reminds you of your sister. It's also easier for someone to send off "competence" cues that aren't backed up by the reality, whereas "incompetence" cues or "bad attitude" cues tend to be linked to something real.)
2. You need to be brutally objective about how qualified your gut is. Has it been educated by experience? Does it has a track record of being right in this area? Do other people agree with your assessment of your gut instincts or are you the only one who thinks they're great? Is there any chance your gut is engaging in racial discrimination or other forms of bigotry? These are all things you need to think hard about.
(And if your gut frequently tells you someone would be a bad cultural fit when that person happens to be a difference race than you or has a disability, your gut is officially suspect and thus is banned from participating.)
As a side note, what are gut reactions all about, anyway? I do not think they're some magical mystery that can't be explained. I think they're reactions to fact-based evidence that you're just not processing consciously. Gavin de Becker makes this point in a totally different context in his fantastic book, The Gift of Fear -- he points out that when crime victims had a bad gut feeling right before the crime, that alarm wasn't coming out of nowhere (although it felt like that to them); rather, he noted specific factual things their brains were picking up on subconsciously that were leading to what seemed like an inexplicable bad feeling but was actually traceable to real signals.