On a barbecue tour, sometimes wisdom sneaks up on you. And so it was in Galveston on Saturday when Leon O'Neal told us his secret to preventing his customers from burping after they ate his smoked meat. Use dry wood, the owner of Leon's World's Finest In and Out B-B-Q said, standing in front of a tall wall of cut oak. "That's where the after belch comes from." In other words, sappy wood is burping bad. Some might put this wisdom in the same category as always buy brisket from the left side of the cow, which we wrote about a…