I was visiting a veterinary hospital earlier this week and a woman was at the counter with her little Dachshund. The dog was on a retractable leash and unfortunately his owner wasn't paying any attention to him. I was carrying my lunch with me and the little wiener-dog wanted some. He was jumping on me before the owner knew what happened.
She apologized and went back to writing her check. The dog again ran over to me and jumped up for some of my lunch.
I don't like retractable leashes for many reasons, but the main reason is not actually the leash itself, but the people at the other end of the leash. They're not paying attention to where their dog is or what he's doing. Lots of bad things can happen when you're not watching your dog. He could jump on people, try to steal their food, eat something harmful, say Hi to a dog who's not friendly…the possibilities are endless.
Unless you're out in a field, your dog doesn't need to be more than six feet away from you. And if you're in a store, on the sidewalk or at your vet office, your dog should be within two feet of you!
The closer your dog is to you, the more quickly you can reinforce good behaviors. Click and drop the treat and boom! the dog is instantly rewarded for keeping a loose leash, for looking at you, for sitting, for whatever. If he's 16' away, he's too far away to reinforce efficiently. And worse - he's far enough away that you can't control his behavior or give him a clue as to what you'd like him to do. So more often than not, you're apologizing for his behavior after the fact, not teaching and managing your dog's behavior.
Another reason I don't like retractable leashes: there's constant pressure on the dog's neck. You're teaching your dog to pull if you use a retractable leash - the only way the dog can get more leash is to pull into the collar. More pressure = more leash. You're setting yourself up to have a dedicated puller if you use a retractable leash.
If I'm going to be out in a field and at least 50' from other people and dogs, my favorite leash is a 20' or 30' plain cotton web leash. The dog has plenty of room to run, there's no tension on the neck, the leashes are pretty inexpensive and hardy.
If you're anywhere where you might run into other people, leave the long leash at home. No one wants to dodge a dog and leash on the trail, in the vet office, or at the park. Carry your clicker and treats and you'll be able to quickly and easily reward your dog for good behavior. Before you know it, that six-foot leash and your attention will produce a more attentive and better behaved dog!