Try an engraver instead of the ink.
[QUOTE=SLP;553377]Thanks guys. I guess from having long heard and read how any foreign odor can scare off some fish it has me paranoid that using ink may spook that big one, but maybe that is the only way to really go. I was hoping for another alternative from someone but maybe there isn't a one.[/QUOTE]
You can try to use an electric engraver to mark the bill with the depths. I personally love to fish with crank baits and always fished that way. I never worried about the exact depth until I started trolling cranks for suspended crappie. Then I started using the Bandit type crank baits that are pretty easy to tell apart. And if I let out enough line and feel them tipping the bottom once in a while I know I'm in the strike zone.
If you did use the ink and it's been on the bait for a while most of the volatile solvents have evaporated away leaving on the solids. Mark them and then let them sit out in the sun for a few hours and I bet that most of the solvents will have evaporated off the crank baits.
While it's true that fish have a keen sense of smell ( most of their brain is devoted to smelling) I don't think it would put the bass off of striking the baits. Bass hit cranks out of instinct. It's a reaction strike a lot of the times. Now if they start trailing the bait they might pick up some odor and may turn away. But I would think that you could spray the crank baits with some Fish Attractant and it would cover up the smell of any tiny bit of ink residue. And if there is any ink volatiles off gassing into the water it would be in the parts per Trillion if that much. Some Dr. Juice or other fish attractant would cover up any bad odors easily.
I wish I had all the boxes that all my crank baits and other lures came in. I'd sell them all for a huge profit to collectors.