Such horse****, do you believe pigs can fly as well?
I have personally used all options while being online (not while invaded) and i have yet to be banned or blacklisted.
Valve also stated that they may permanently terminate your account if you buy cd keys from non authorized CD-key resellers, i have over 300 games on my steam account that has been aquired from resellers for over 6 years. As long as you don't buy keys that was stolen or activated by using vpn there is little Valve can do.
I personally saved thousands of dollars by cutting Valve out as the middleman, i don't plan on paying 50 euro for a single game ever when i can get it for 25$ elsewhere.
[Edited by sauced, 5/18/2014 9:49:55 AM]
[Edited by sauced, 5/18/2014 9:54:59 AM]
You are playing with fire. We cannot guarantee the safety of your Steam account. You do so at your own risk.