When I first got Duke (he was 2yrs old at the time), he was very ill mannered on the leash. Horrible. He pulled like a gator was at his tail, and sniffed every spot and would probably have stayed at each for 10min at a time (and yes, the whole drooling, shaky jaw, etc). Honestly, it's all in the management and training of the dog.
Once he was acclimated to the house and to us here.... I put him on a prong (he'd never been on one before from what I could tell), took him out for a walk and corrected him each and every time he went to sniff. In my opinion, if they can't behave and control their noses... then they don't get that option at all. I made him walk next to me for the whole walks. We don't walk to go potty.. that's in our backyard off leash. So they don't need to do that on walks. There's no need for sniffing.... that's a luxury for well behaved dogs that listen. Lol.
Not saying Berlin is bad... he's young, he's a goofy guy right now... and you just need to be a little more strict. He needs to understand what YOU want from him. Make it clear for him to easily understand.
My dogs know when I say "free"... they can walk to the end of their leash (no pulling though! I always ask for bit of slack) and can do whatever they please.... sniff away! BUT when I catch up to them, they must keep walking... sniffing that spot is done. I don't mind that because they respect me, my rules, and in return... they can be dogs and sniff to their hearts content. Once I say, "with me"... they know to get their butts next to me (non-focused heeling). We work with this a lot, and it's very useful here. We have some areas that the sidewalks are small and it's very populated, and others that are fairly open and no one is usually around. I need them to respond to my commands so that we can all enjoy our walk and in the end, remain respectful to others around us.
I'd maybe try this with him.... for now, just be strict. 100% next to you.... not focused, but heeling beside you. Once he understands this... teach him "free" or... "go ahead" or "ok".. whatever you want to use.... when he goes to pull...... "no pulling.. come".... start over. He doesn't get what he wants (to go forward) until he behaves. Then when he goes to sniff something on the free walk.... don't correct him... keep walking and once you are next to him... correct and say "Ok lets go"... or "no, come on"... etc. Let him know that this is when he needs to keep going. If he doesn't obey this... go back to non-focused heeling... start back again. Always praise when you get what you want. Make it very black and white for him.
Leash manners 101.
-Pakros von Jagenstadt "Duke" (01/06/10) -CGC