I found a nice way to deter some scammers

Only useful if trading for things outside of TF2
I don't know if anyone else has thought of this before me, but someone probably has.

If you're trading a TF2 item for anything that cannot be traded through TF2, such as money, Steam games, blowjobs (lol just kidding), etc. then ask the person you're trading with to send you a TF2 item trade of equal value (keys, buds, hats, metal, whatever) and tell them you will hold onto their keys until you receive whatever you were originally trading for. If they don't give it to you, you lose your item, but you get to keep their keys or cosmetic items they sent you instead.

But, if they hold up their end of the deal, you have to hold up yours as well, or you'll be a scammer too.

Remember, keep an eye on the chat box in the trade window. It will show everything you and your trade partner do. After both of you click the Ready check box, make sure the items they are offering you are the ones you are supposed to receive. If they quick-switch, the checks will disappear and you'll see in the chat box what was switched. And, just to be sure, always be the last one to click that big green button.

This is a bad idea. It would be to easily abused by people saying I will hold this and then taking off with the item and the money. This is why trusted Middlemen exist, though even then it is risky if either side is lazy as there are many impersonators out there.

And I knew that would inevitably happen if people started doing this. The scammer becomes the victim, and vice-versa. Oh, the irony. That wasn't my intention, just for the record, but there really is no way to prevent scams regarding items that are traded outside of tf2. Except not trading. And that's why I don't trade.

I've never been scammed, and I do trade every now and then...

yes, some attempted... but if you know your stuff, then that will fail.

The word you are looking for is "collateral," I believe...

I did this once or twice.
Someone wanted me to not sell an item, I told him if he wants it that badly to give me a key a while so he'll have to buy it.
He bought it about the next day.


Another time this happened and they gave me a key, I noticed that demand for my item was dropping and the buyer was not able to even get another key yet. So I said "screw this" and gave the key back to him.
The problem is if they don't hold up their end, and they want to fight you over it.. you got to ask yourself "is this worth it, or should I just give it back?"

So I try to avoid these unless if I really believe the buyer will come through within a day or two.