blackwater wrote:

It has been a long time since I read Doyle.

With regard to the "fairness" of Sherlock, there are definitely issues. He often goes off on pretty esoteric chains of reasoning. Like noticing that someone has a certain kind of soil on his boots and associating that with a certain part of London, or something (this example is just made up, I am not an expert on the stories as you can tell!) But that kind of thing. The reader has no chance to make that kind of connection which makes it feel less fair to me.

There are a few cases in the stories where the connection does seem reasonable. The aforementioned dog is one of them, which is one reason it's such a memorable plot hook.