A friend recently commented about a young man walking his puppy on a flexi or retractable leash and how the pup was running all around with no control and up to her and her dog. This time there was no interaction between the dogs and the young man continued on his way. This may not always be the case.
Many people seem to think that they are doing their dog a favour by giving him/her the freedom to run about, but on the contrary. Their dog is not learning how to walk properly and is completely out of control. A retractable leash has a button to push to stop the leash from extending and anyone using such a leash should learn how to use it properly. When walking on the street and another person approaches alone, or with their dog, the person should retract the leash immediately to shorten it and lock it in that position. Not every person or dog wants to have an out of control pup in their face.
Ideally when training your pup you should be using a good quality 6 foot leash so your dog is under control at all times and train your dog to heel beside you and not drag you all over the place. When that puppy grows up you will never be able to control him and walks will become a challenge and not fun.
Retractable leashes can be a great tool to use when in a park or open area and you are having some free time or alternatively when practicing recalls (come when called), but certainly not on a city street until the handler can properly use that type of leash.
A retractable leash should also be checked on a regular basis as the cord can and does wear down due to the friction of the lead constantly going in and out, and one day it can just snap and your dog will be gone. So if you are going to use a flexi leash, learn how to use it properly and train your dog to go for a walk with you rather than the other way around.