That's right on the money. I NEVER chase Henry for anything or react in the slightest, so there is no fun for him in running away with contraband. Most things he brings to me for a swap, and if he doesn't bring it straight away, he drops it the minute he sees my hand going to the treat jar.
This approach was a life saver recently when he found some cooked chicken bones in the park. He was a little distance away from me when I saw him lie down and start munching on something. Because we have no habit of chase in these circumstances, or me taking things from him (only him GIVING things to me) he didn't run off when I strolled over and I was able to put a hand on his harness, and pull out the long bones that were heading down his throat. Other dog owners were having a terrible time trying to get the bones off their dogs, trying and failing to chase them down. This wasn't a circumstance in which I expected Henry to voluntarily swap the contraband as it was such a high value food item. But because I very rarely take things from him, there was no problem doing it when I needed to.