A madman crashed in Luby's and started shooting. A madman walked into IHOP and started shooting. The same can be said for Virginia Tech, Columbine, and other places. Those "horror stories" don't keep me out of restaurants and schools. Similarly, people are accidentally shot every week. That doesn't keep me from handling firearms, either.
Gun shows are a great place to see and handle a wide variety of firearms and ask questions of knowledgeable and reputable dealers.
Obviously, the simplest way to ensure you're not the one who creates mayhem, simply check to ensure the magazine is removed and the chamber empty before handling the firearm. If a dealer hands you a firearm without checking it first, simply do not accept it and ask they clear the firearm.