Our dogs deal with distractions in every search all of the time. Most of the distractions are low value compared to the target odor and the promised reward. Some distractions can be truly irresistible to even the most focused dog. Our hope is that our dogs will seek out and find the target odor, even if it means passing over a burrito in a duffel bag, or the scent of a deceased critter in a wood pile. Our biggest fear is that our dogs will take such an interest in a distractor scent that we'll get duped into thinking that a stick of butter in a box is the target odor. How do we put our fears to rest and make our hope the reality? How do we get to a place where we're confident in our dogs to always choose target odor above all other scents?
Always Deliver a Clear & Clean Reward - Not only is it important for your dog to get rewarded at the source of the target odor, but it's also important that you not drop food reward elsewhere in the search for him to eat. The clearer your dog is on what pays (finding the source of the target odor), the easier it is for him to seek that out above all else. If your dog usually finds a dropped treat in the search, he's being rewarded for efforts that don't result in locating the target odor. If you encourage him to find dropped treats, beware. Behavior that's rewarded is behavior that's repeated. Maybe, he expects that you also want him to find food in target-odor-only searches. What happens when he encounters food in the search, but he can't just help himself to it? Hopefully he doesn't offer a final response. Your dog should get paid only by paired reward on the target odor or reward you deliver, anything else he enjoys in a search will make it harder for you to read his communication.
Confront Distractions Head On - If your dog really has a problem with certain distractions, avoiding them is not going to make the problem go away. Rather, your dog needs some clear communication on what pays and what doesn't.
Some dogs respond well to a simple search exercise with three boxes: one containing the target odor, one blank, and one containing a high value food distraction (the food should be in a container within the box). Let the dog investigate the three boxes and pay him immediately for interest in the target odor box. If your dog wants to get the food in the distractor box, be patient and let him make the decision to leave the box and search for target odor. Do this a few times with lots of rewards for choosing the odor box, then add in several more blank boxes and watch your dog hone in on the target odor box without much waffling.
Some dogs show great progress working a search with 6-8x the number of distractor boxes to target odor boxes. Make sure to draw a diagram of your container search, and label all boxes clearly - you don't want to reward your dog for finding banana nut muffin! This exercise seems to work best if the target odor boxes stay put and the the distractor boxes move around. Again, if your dog is interested in a distractor, let him investigate and leave it on his own. If you drag him away while he's still trying to get to that rabbit pelt, he'll just pick up where he left off the next time he passes that distractor.
Be an Observer - Definitely take advantage of watching your dog in K9 Nose Work searches to see how he investigates a pee smell or food item differently from the target odor. But, also watch your dog in all other areas of his life. How does he look when checking out that tree on the corner that every dog in the neighborhood makes a pit stop at? What's his nose do when you set a tupperware container full of leftovers out on the table?
If you watch all the ways your dog investigates non-target odor scents, you won't have to wonder if that bag in the container search he froze on, then left, needs to be checked again.
And, while I feel for anyone who has had to make a false call on a distractor item, don't get too down or yourself. Your dog is not suddenly also alerting to corn on the cob or old gym socks. Most likely, you misread his initial signs and encouraged a second look at the item which then gave it some kind of value in your dog's world, and the two of you kept fueling the fire of false alert, until he gave you what looked like his behavior at odor, and you made a wrong call. Your dog doesn't get paid for your mistake, it's not suddenly a better gig to false on food and get nothing than it is to get rewarded for finding target odor. It is worth thinking about how your dog is different when working to and sourcing a target odor versus smelling distractors; pretty much every dog is different in some way.
Keep the Target Odor Valuable - Yes, it's good for our dogs to put the target odor in direct comparison with high-value distractors, but this works way better if the dogs already consider the target odor to be an easy-to-find source that consistently brings a reward. Make sure your search scenarios feature hides that promote clear communication from your dog. This doesn't always mean the search needs to be simple and the hides super accessible, rather, you and the dog need to be on the same wavelength regarding rewardable communication. If you're running searches with your dog and he routinely displays source odor behavior and/or gives a final response three or more times before reaching the actual source of the hide, you need to adjust your searches. This kind of practice won't help the team, especially during searches where distractors will be present. On the flip side, if your dog does searches that allow him to confidently work to source and allow you to meaningfully time rewards, he should have a strong desire to find odor in any situation.
When you & your dog are practicing K9 Nose Work and confronting distractions in the search (planned or unplanned), try to remember that you get more information when your dog investigates a distracting item or area, even though it may result in your dog peeing on a bush or pawing at a bag with potato chips in it. Practice is not a K9 Nose Work trial. Peeing in the search or false alerting on a distractor item does not mean your practice session - or your learning opportunity - is over. Take something positive from every search experience and use it to inform your training going forward. You'll never know when observations from a training "failure" will help you to read your dog and achieve competition success.