Ever been aboard a boat trolling identical lures, and had one lure consistently catch more fish than the other? You probably even switched the sides of the boat the rods were on to see if that made a difference. Chances are the "good" rod/lure combo kept out-catching the other no matter where it was placed.
Chances also are that the successful lure was running "true" while the other needed some fine tuning. Even straight out of the box, many lures need some tweaking to run with the action and at the depth they were designed for. In fact, some manufacturers even supply special tools for bending eyelets or weights for custom balancing to get their baits to run to the best of their abilities.
Diving crankbaits or stickbaits are particularly susceptible to being "off" tune. Anglers who realize this will attach their lure-of-choice to their line and, if trolling, get the boat to speed. If casting, they will make a few practice casts and work the lure back as if they were fishing. Both will watch the lure closely as it goes through the water, making sure the lure runs straight, dives to the desired depth and doesn't run off to one side, turn one side higher than the other, spin outright or flop over and burst to the surface. The last two radical scenarios are easy to see; minor glitches such as a lure that runs slightly off center or doesn't wobble evenly may not seem like a big deal. Unless you're a finicky fish seeking any reason not to smack that meal swimming past!
Some of the time, the culprit causing the off kilter action is the angle of the eye to which the line is tied. That wire ring-eye must be precisely aligned with the body behind and the lip below to allow the lure to dive straight down and to run and wiggle evenly from side to side. Note that I didn't say "perfectly" aligned, for some lures are better balanced and run truer when the eye is bent to a tiny degree to one side or the other, and the only way to determine that degree is by running and watching the lure as it proceeds at speed through the water.
Needle-nosed pliers are the tool of choice for tuning most lures. Most of the time, when tuning a crankbait that is turning to one side, you use the pliers to bend (not twist) the entire eye very slightly to the side opposite the one it wants to turn toward. Keep bending and testing until the lure runs true.
Artificial lures aren't the only baits that need tweaking from time to time. Anyone who has cast or trolled a nightcrawler knows that the popular live bait will spin and twist line unless it is weighted or hooked just right to allow it to move through the water without spinning. That
usually means hooking it lightly through the extreme end of the worm's nose-or "fat" end. Test each hook presentation until you determine the bait will proceed straight when pulled through the water before fishing.
Knot The Answer
Another factor that affects how a lure runs is the knot itself. A clinch knot cinched down tight to the eye-but off to one side a bit-can affect a lure just as much as the eye itself being off-center. That's why many anglers prefer a Uni-knot or some type of knot that secures the lure with an open loop at the end of the line. The loop allows the line to run loosely through the eye and the bait to have a full, unimpeded range of action without fighting the restriction of a tightly knotted line.
If you prefer to cinch-down your knots, make sure the knot is aligned with the eye. Also, make sure the tag end of the line is cut short and you don't have 1/4 inch or more of stiff mono sticking out to one side of the line-to-lure junction, where it impedes water flow and causes the lure to run off kilter, the result being your baits getting the cold shoulder.