What do you think about this method?
I've read an article about this way to deal with the aggressive dog in the presence of other dogs. It says to bring your dog on leash near another dog, but not too close; even before any sign of aggression, to cover its eyes when he looks in the direction of the other dog, then praise him if he looks at you.
I never tried it. I don't feel it works for me, but I would like to know your opinion.
I have an ex-stray neutered dog (about 6-8 years old) which sometimes would try to attack the dogs we meet, especially when on leash. When he first came to my home, he would attack 3 of 5 dogs, mainly strays. I was not mad at him, as he had a lot of previous street fights to survive. On the other hand, he is extremely friendly to some dogs and he may just ignore others. He is a great friend to my younger dog, a Giant Schnauzer of 1.5 years old; despite he imposed himself as a leader, and he may still make some noise, he has never ever bitten the puppy. Not to mention he is perfectly nice with kids. Now, after about 2 years, he would behave aggressively towards 1 of 50 dogs we meet, and these are mostly his previous 'competitors'. He would also growl or bark sometimes because of fear, sometimes to show dominance. He is very responsive to food, and that's how I tried to solve the problem. Food or prong. But when it happens, I am helpless, he wouldn't mind and he gets himself pronged.
Once a day, we all go out. The rest of our walks are separately, one dog at a time. When we are together, of course, my younger dog tries to go one step further and to bark like thunder, but for the moment, fortunately, he is generally dog friendly and easy to be stopped with 'NO'.

control the dog though OB. In my opinion, sticking your hand anywhere near a dogs face when it is in 'that mode' is just asking to be bit.

Not only are you asking for stitches, but you are very likely to RAISE the dogs level of aggression by increasing the stress of the situation for the dog. Now he can't see. . .more stress/aggression is possible.

The covering of the eyes is a old KNPV method of training food refusal.Trainig this way for the problem your stated will only end up in a trip to the ER.At 6/8yrs of age & an unknown background(stray)& with a lot of water already passed under the bridge,consider correct management practices including walking this dog solo.Rdgs Mark.