In all, I think I've been pretty lucky. Over the years, I've come across all sorts of people. Some were sweet, funny, endearing, brilliant, downright adorable. Some were rude, obnoxious, creepy and offensive. Only on a few occasions, though, have I come across someone who I felt was absolutely evil.

A few years ago, our family dentist stopped accepting our dental plan. It felt much like being dumped on the eve of prom. We scrambled around to find a practice that would honor our plan and ended up at a storefront outfit with plastic lawn chairs in the waiting room.

I made an appointment for myself and my then-high school-aged daughter, Molly. I went first. The dentist was a tall knobby young man with a soul patch, one of those clumps of hair sprouting from under his lower lip. He was brusque to the point of rudeness. He performed a quick exam and loped out of the examining room. I missed my sweet chatty dentist so much that I felt nauseous.

Next was my daughter's turn. She wasn't in the room long, either, but when she emerged, she was in tears. I was horrified. What on earth had happened? She couldn't explain it precisely; she just said, "He creeps me out. Please don't make me come back here."

The dentist? Barton Corbin. Seven months later, he shot his estranged wife and then attempted to make it appear a suicide. He left her body to be discovered by her young sons. It was later revealed that in 1990 he had killed a former girlfriend, disguising her murder as a suicide. He is now serving two life sentences after pleading guilty to both murders.

So here's the question: Was my nausea and Molly's tears a normal reaction to a bad experience with a ham-handed dentist or was it something more? Do we have an internal radar that responds to the black core of depravity inside some soulless individuals?

I suspect we do but it's often ignored. It's only in retrospect that we recognize the feeling for what it is, a visceral protective response to very real evil.

I thought about that when I followed the tragic events in the Meredith Emerson case. I imagine I can see it now: a beautiful mountain trail on a bright winter day, two friendly dogs and a young woman making casual conversation with a grizzled old man. It would be so easy to ignore those vague feelings of dread, not wanting to appear rude by making a hasty retreat.

Sometimes I think a lot of survival instincts have been civilized out of us. We worry too much about appearing impolite or paranoid.

I try to teach my girls to listen to their guts as much as their heads and hearts. If something doesn't feel right, assume that it's not. If you're wrong, you can always apologize or laugh it off later. If you're right, it might save your life.

Teressa Glazer is a Gainesville businesswoman. Her column appears frequently and on gainesvilletimes.com. First published April 4, 2008.