Don't name your variables after types:you wouldn’t name your pets “dog” or “cat”

Name your variable in a way that makes as clear as possible what the variable is used for.

He uses the example of "userMap". I think its mistake is not saying what the mapping is for. Names to users? Phone numbers to users? Emails to users? Its mistake is not calling it a map, which tells the reader that a variable behaves as a mapping. (And if it's not actually a map, then don't call it a map.)

"UsersMap": doesn't add much value, what are you mapping?

"UsersById": now this is my style

My cat has a name, but I just call him "cat" most of the time.

The point being - if the name is not ambiguous, it's fine.

The correct naming is of course "originalConfig" and "updatedConfig".

I also inherited a bunch of circa-2005 ColdFusion with aptly named variables in CamelCase which are much easier to understand.

varUsersTableID > pointer*Freya any day of the week.

“He’s the only one. He knows I’m talking to him.”

I would if I could not tell just by looking at them what species they are (and thus what I can do with them, what to feed them, etc) among 200 other animals in my house.

To torture the metaphor a bit more, of course I'd eventually remember which one is which because they live with me. A better metaphor is the feral cat that shows up on my doorstep once a week looking for a handout. I've slept since then, what are you again?

I see it as a courtesy to myself than those that come after me to provide relevant context to a variable name. If the type in the scope of the variable is meaningful to its use then I will include it.

Good or bad code tells me what it does, rarely does it tell me what its supposed to do.

犬 = Inu = Dog