I deliver and control “go sniff”opportunities much like I control food treats. I give “go sniff” to reinforce my dogs for paying attention to me.

If your dog loves to sniff, stop viewing this as a problem! The interest in sniffing around isn’t just a “distractions,” it’s a very affordable (free!) reinforcement that you can harness and deliver to reinforce behaviors that you like.
How? You put the opportunity to “go sniff!” on cue, and then deliver it, regularly, generously, as a reward for behaviors that you like. There is one little trick to it though, and the trick is that your dog needs to know and trust that you are going to deliver these “sniff” opportunities. Imagine if your dog was starving and didn’t know that you were going to feed him. That’s the sort of behavior you might get from a dog who needs to sniff and doesn’t know that you are going to give him all the sniff he needs.
I’d been doing giving my dogs “go sniff” opportunities for quite a while, before I started to really understand what was happening and what a gold mine of reinforcement I now had at my disposal. My eye-popping awakening came at an AKC rally and obedience run-through event, held in a huge barn/indoor arena. The facility owner told me they regularly had horses in there and “normally, we keep chickens in the corner.” They might as well have built the whole facility out of hotdogs, as far as my dog was concerned! My young dog was much too excited to eat treats, and so I settled him on his mat and watched competitor after competitor walk in with distracted, scent aroused dogs, take a look around and leave, saying things like, “not today!” and “I don’t think so!”

I started to warm up my dog. I gave him a sit cue, and then rewarded it as he had hoped, with a limited sniff opportunity.
Whenever I deliver a “sniff” reinforcement, I deliver it in bite size pieces, just as I do with hotdogs. My dog is on a six foot leash and I remain stationary until he’s done sniffing that limited area, and looks up at me for his next cue and reinforcement opportunity.
I always ask for a stationary behavior before delivering sniff reinforcement, so we heeled up to each aromatic corner of the barn. I delivered a “sit” cue, and walked around my dog, and then rewarded with “okay, sniff!”
When you have a hundred pound Czech bred German Shepherd, the cost of food reinforcements can be substantial, and there I was, discovering that all I had a literally limitless supply of free sniff reinforcement!
Previously, I had been using “sniff” opportunities to teach loose leash walking. I used telephone poles and fire hydrants, along with a little food in between, which resulted in a somewhat variable delivery of reinforcement reinforcing nice leash walking behavior. It’s important to make a clear delineation between the end of cued performance and the beginning of the reinforcement opportunity, so I always ask for a stationary behavior, or at least some hand targets, before I deliver “sniff!” So we would heel, walk trott, and come to a halt near a potentially smelly spot. Today, I might cue another few behaviors, maybe sit pretty, hand targets and then reward with “go sniff!”
Part of my trick included head halter training. When you have a dog as powerful as mine, head halter training is essential for safety, both for me and for my dog. The head halter meant my dog couldn’t drag me around collecting sniff reinforcement whenever or where-ever he wanted. So my dog is completely comfortable and relaxed wearing a head halter (see https://youtube.com/playlist?list=PL1E6379E57F518AF0 ), and it helps me control sniff reinforcement, and deliver it after behaviors that I like.

But even if you have a tiny dog who doesn’t need a head halter, you can teach your dog to respond to sniff reinforcement the same way they respond to hotdog reinforcement. Rather than ignoring or pestering your dog when he is sniffing around, you need to anticipate his interest and start controlling and delivering “sniff” opportunities the same way you control and deliver food: intentionally, not accidentally, and immediately after behaviors that you LIKE.
As time has gone by, my dog has learned to glance towards things he would like to sniff, and then he look back at me, hoping I will give him an opportunity to earn the sniff. When I let him off-leash, I often say, “okay, go sniff!” and I think of those times as being his “sniff-meal” times, similar to the way he experiences food-meal times. He doesn’t ALWAYS have to work for sniffing reinforcement!
But when you use sniff as reinforcement, it means you really need to pay attention to your dog. You need your dog to trust that you understand what they want, and you will deliver. When your dog trusts you, they can ignore smelly sniffy stuff the same way they can ignore a bowl of meat on the floor, confident that you are going to deliver, and they don’t need to steal it.
