I do intervene in trades, and I do work for Steam Support. If someone says they need me to "check your items" for fakes/duplicates/glitches/whatever, they just want trade assurance. There is such thing, and this is a signature trick used by scammers to steal from newcomers to CS:GO.

If you think I scammed you, and you're adding me for your items back, read this first. [ forums.steamrep.com ] It wasn't me, you were scammed by an imposter who copied my profile. Yes, I can get your items back. .

I am a SteamRep administrator. Please verify my identity by copying and pasting the URL of this page into SteamRep.com before anything related to SteamRep or trading. If are viewing this in Steam and don't have a URL bar visible, right-click and select Copy Page URL to copy and paste my URL.

I am not a middleman. Do not add me to hold your items. Do not post comments asking me to add you for a middleman, or to help you find a middleman. Doing so may make you a target for impersonators.

If you are looking to report a scammer and have them marked, please fill out a scam report instead of adding me. I do not accept reports via Steam chat. http://forums.steamrep.com/forms/scam-report.2/respond Please note, SteamRep cannot return your items.

If you are tagged on SteamRep, do not add me to have your tag removed unless I specifically asked you to in your appeal. Make an appeal here: http://forums.steamrep.com/forms/appeal.4/respond
Don't ask me to expedite your appeal.

If you're adding me for anything else related to SteamRep, I ask that you send a private message in the forums first or I might ignore you.

If you're adding me for a trade, please send a trade offer . I might or might not accept your friend request otherwise.

If you're adding me for any other reason, please post a comment on my profile. I automatically ignore any friend request from private profile, new, or low Steam level accounts unless you give me a good reason to accept or it was discussed previously.

Do NOT post "+rep" comments on my profile, and don't ask me to post it on yours. Profile reputation is not worth anything, and you should not trust it. If you perform a trust trade with me, I will provide you with a link to my reputation thread.
More on rep threads: http://forums.steamrep.com/threads/what-constitutes-reputation.12391/