This is exactly what SteamRep tries to prevent people from running into, but what if you are stuck with that person trying to scam, and you either don't realize it's happening, or you want to get out of it as quick as possible? I can lend a hand. Spot it from the start: I want to use this example for spotting a scam in action, using my personal favorite from Valve, Team Fortress 2. You and another player have agreed to a trade on one item for another, because you believe they are the same value. You are trading for unusual hats. The other person sends a trade to you, and you both have the window open to set out your items. Now, let's make it clear that when you discussed trading your unusual and the other person's unusual, you and the player never specified what the effect was on your hat or their hat, and this presents a possible price difference. For the example's sake, You both have a Team Captain, but the reason you decide to trade is because of the other player's claim to it being "cooler"; beware of that excuse. You and the player place out your unusuals, and the other player rockets his cursor to the Ready to Trade button, and you see he is green; ready. You slide your cursor to your Ready to Trade button too, but then your Guardian Angel (me in this case) asks you to LOOK at what you're trading for!! But everything seems fine, I mean, just look for yourself! Team Captain being trade for "The Totally Radical and Awesomer Hat" Check the effects, if you require any more red flags for this trade. (You have a Burning Flames Team Captain, he has a Massed Flies Team Captain.) I'll even explain the problem, A Massed Flies Team Captain is worth roughly 12 buds; ~$440 (2014) and the Burning Flames Team Captain is worth 133 buds; ~ $5000 (2014). This example is the worst-case-scenario for a person who doesn't know much about pricing, but now you have a good idea of what it looks like for a scam situation. The signs might not be as easy to see sometimes, or you might overlook something. Always do a double check on prices. Never use server pricing plugins; those are all kept up by admins and therefore some admins might... Anyways, you should never go quickly with unusual trading, check for a duplication(if you care), check that the hat has the effect you wanted, and the price of both hats, so that you don't accidently lowball or trick the other person. But most importantly, make sure your are both content with the trade, because who cares about the trade if one or more of the participants is happy with what he/she got? There are cases where you need to sacrifice, but a scam- to me -isn't really a scam if you agree to an imbalanced exchange, or if you are both ok with what you received. I wish all readers good luck in the trading universe.