When trading, being cautious is advised to prevent getting scammed of your gear.[]
One common example involves a player promising to carry in order to receive an equipped item (typically a legendary or certain armor piece). Some solutions to this include refusing their offer or not fulfilling their request until they carry a sufficient amount and also supply a better replacement.
Another common example involves a player promising to upgrade an equipped item (typically a legendary or certain armor piece). The best solution to this is to refuse their offer.
Yet another example, though rare, is targeted to newer players who don't know how trading works and the mostly agreed-upon values most others do. This scam usually involves a newer player, usually in Desert Temple or Winter Outpost, having good luck and getting a legendary. Then, the person attempting to scam may get an item or spell from a higher level, often from Boss Raids or above. Then, said item(s) will intimidate those newer players with stats and sell values in the millions, and level requirements well in the hundreds, who don't know that those items have practically no value. Then, the scammer will ask for the legendary or collectible the player is wearing for the items they are trading. The player, potentially unaware of the level requirement system, will be desperate to get the gear and be left in the dust when the scammer leaves the lobby or ignores them.
Another example is coined "trust trade", where a player has a valuable item and they give it to the scammer, who promises to give it back or give their offer in another trade. Sometimes, the scammers claim they have an alternate account with their offer. The scammer then leaves or ignores them, just like the scam above.
Please be careful when trading. If you feel like you're getting the worse end of the deal, decline or ask them to add more. It's always a better option than losing your most prized items.