They have strict rules and they can ban you easily depending on what you have done. Its on the rules if you want to see the punishments.
Yes, as far as I remember, there is a warning before they ban you but in my case when I was an an active member there few years ago. I got into a vocal fight with some jackass and got banned for 30 days. That was enough for me to quit GT that time but I just joined back today. The problem here is it loads very slow and it kills my time.