My house, my rules, I'm Boss 
As I walked into the house with my regular 'boy', the visitor lunged, growling in an alarming manner. I had ready a fine water spray which I used on his face: he stepped back, gave me a sideways glance and walked away to consider. When he did it again, I only had to pick up the water spray for him to back off my regular 'boy'. Instigating me going through doorways, gates etc. first reinforced that I *am* to be listened to! After 2 days he was more relaxed as I had given him ground rules, never necessary before with any of the dogs who visit here.
As for not stroking a dog wearing a muzzle - I would certainly approach the owner though and ask why 
usually there's a reason, a springer in our village eats poo of all kinds and her owner is a little fussy so the dog wears a muzzle in the fields. Shame ain't it, a bit of sheep poo breath never did anyone any harm ........ 
I sorry to learn that Roger has preconceived ideas - I thought it was the behaviour he was judging not the breed! Another one to cross off my C.mas card list 
Our visitor has returned to his home now and it's Oh So Quiet ........
you must be so careful when using aversives on what sounds like an already frightened dog.
( confident dogs do not kick off and lunge as you describe)
Dogs make all sorts of weired connections between events and their environment and it is hard to let the dog know exactly what you are punishing him for.
If you do need to distract a dog with these methods then it is also important to train the dog an alternative more appropriate response otherwise dogs will learn you are to be feared and avoided and is that what you want from your relationship with dogs.
I am the leader and the boss in my house, but I do not have to go shouting the odds and spraying water around the place and I have in the past year rehabilitated a reactive dog ready to be PTS for people aggression before he came to me.
Punishing my dog who already had a mistrust of humans would have been counter productive to say the least.
dogs often learn to ignore punisher's anyway so what would you do if the spray stopped working? Where do you go then?
Do you start smacking the dog?
IMHO it is much better to train for what you want and be consistent with ground rules and your cues.
I have built such a super bond with all my dogs and though I do use tone of voice to warn them of my displeasure at their actions on occasion I always try to turn the negative into a positive behaviour I can reinforce.
I also do not stroke any dog muzzled or not without asking the owners permission.
I never force my attention on another dog but if it chooses to come to me for a fuss I will gladly oblige.
Mark
