Hmmmm just a few times, when I was selling some steam accounts :D

I've scammed people hundreds of times. It's real easy to do and feels very satisfying after...oh wait. Misread your post. Ignore that bit.

Never. Don't trade much really, and not out of the trading window.

I once lost Borderlands GOTY that was worth about 10$ at the time. That's all.

Only once, wanted to trade my Dota 2 gift for Left 4 Dead 2.

I was new to trading at that time and the guy offered me a Left 4 Dead 2 key (does it even exist?) and I went first without checking his profile or anything lol

About 4 times.

0 and wont happen...

I got scammed once, I was new to trading and got fooled by an impersonator...
Learned my lesson and now i'm trading happily and safely ;)

Never, I don't do deals with bitches

Only once, and it was a bundle key for Rig 'n Roll so no big loss. (I suspected I was going to get scammed but went with the trade anyway since I figured I didn't have much to lose.)

Revenge -rep is against the rules.

mainly applying to everyone that gave him -rep that isnt Amoox.
I know SG has rules against calling out, I'm pretty sure it isn't in the ST FAQ (not sure what their rules are on it)
But, I'd remove the link just to be safe.

Aside from that, sorry to hear about that. The vac ban would've tipped me off :/

None.
A few attempts from others, but nothing happened at last.
And neither in Steam or out from here.

Have a nice day :)

Once, one my very first trade though :/ Got scammed out of the first two AC games, setback of 5€
Was clueless at the time though, learned my lesson. He was known scammer in SteamRep, just I didnt. Know SteamRep back then
And funnily enough, I "traded" for Anno 1404, which just got rereleased recently :D

Zero. Generally, if I dont trust someone, I dont trade. If I get a bad feeling and its a code I care about, I wont give it or go first.

Never.

A loong time ago, unboxing a unusual with my first key on Tf2, I got to wear it for 5 minutes before I traded it for 3 normal craft hats ... I suppose I was just used as a noobie :/ .

I got scammed once, I agreed to give 2 keys for one, went first, that person disappeared and removed me. When I put negative rep on steamtrades, he did also put negative rep on my account, even though he scammed me :(
I have opened a ticket one week ago, still no response :(
I stopped trading and will be too much cautious next time when I do.

Once on my first trade... (lost Thief) :/

Second trade i made, lost 1 key, Arma arrowhead. It is not like i was going to play it or the one i was going to receive (HUUUUUUGE backlog), but still. You feel good when you give a game, you feel bad when a game is taken from you.

Twice. Once I lost 3 keys selling BF3, second time I paid 4 gifts worth 2keys+ for a 1 ref item :(

Once and it was all my fault. I was too eager and wanted the game really badly so it clouded my common sense. I didn't even suspect when he refused to go first even though I had more rep than him. But lesson was well learned and now I'm extra cautious when trading with low rep people.