Nostalrius Begins - Quality wow vanilla realm (1.12)

Hello all and GM team
I often read forum of our favorite server.
And I saw a trend that began to disturb me. Specifically, many bans for suspected hacking account.
Tell please what is a suspicion of hacking an account? I am as an honest player would like to limit account from this.
Why do I have a question? Because I know that one of the suspicious behavior is considered to enter the game of not peculiar IP-address, but I often travel and therefore for me it is normal.

Can you share how it is considered that an account has been compromised?

Don't buy or sell an account.
Don't publicly post your account name or use it as your forum name so no one tries to guess your password and sell your account.
Don't fall for phishing attempts on buy cheap nostalrius gold websites.
Etc.

I know what I should do. to protect my account.
I want to know what it means to "suspicion of hacking" by our gallant defenders GM team