A wagging tail is an indicator of an agitated emotional state, not necessarily friendliness. It can mean "Happy to see you!", "Get the fuck out of here!", "Help! Help! I need help!", "I am being scary!", "Look at me!" or "Hey! There's something over there!"
You have to read the accompanying body language as well.
+ one star for this, I was thinking the same thing. I'm wondering how much of that STALKER video game is fictional after seeing all this shit from Russia.
In Russia, like in most countries, police simply shoot them on sight. In hotter climates wild dogs are a serious health risk, since their feces particulates and causes all kinds of sicknesses. They will also kill children from time to time.
Dunno how it is Russia, but over here in Romania they are a serious problem, aggravated by the fact that old people (that make up a large chunk of the urban population) feed them and hide them in their apartments when dog-catchers try to round them up. They are very docile to the people in and around their territory but become very aggressive towards strangers.
Not that I'm on the side of the dog-catchers, since there was a scandal a few years ago about the horrible conditions in the shelters and the fact that the people hired by the city to euthanize the dogs sold off the medical equipment and poison and simply beat them to death with crowbars.
I have some Mexican friends and have spent a little time there.
Animal control is pretty shitty but the wild dogs in the cities are the most docile and meek dogs you have ever seen, because if they show any kind of aggression, people will fuck them up.