They add a valuable item such as Heatwave at the beginning, then they add a lot of other stuff. Stuff that doesn't have a price, limited stuff, etc. When they've added so much stuff that their Heatwave has disappeared in all the stuff, they remove the Heatwave and press accept. A lot of people don't scroll up, and accept.
This is something you can't see unless you've scrolled to the top.
They're claiming they need to clear their inventory, or they just want to give you stuff.
A lot of people claim they know how to "Duplicate" an item. This is NOT true, and does not work.
Once you give them the item, they will take it, and you won't get anything back.
Be careful when you're trading wheels like white lightnings. Wheels that's painted can look a lot like the normal ones. They usually swap the painted onces with the normal while you add your stuff.
This is extremely hard to notice if you're not careful. (PS4) Press L3 on an item to see details about it.
(Only if you have party chat open)
They add their items, so do you. When trade is ready, the person starts spamming trade button, and at the same time, they remove the (main item). You press accept not seeing this, and because you have party chat up, you're not able to cancel the trade.
A lot of people claim they have a lot of reputation (+rep), and that they're a trusted middleman. Never use a middleman you do not trust, and never trust steam profiles with rep comments. Use our Official Middleman to make big trades or real money trades.
This also goes with PayPal/Paytm. If you're trading with Paypal/Paytm, use a trusted middleman.