- You should never trust someone with a private backpack or profile. Scammers often use this to cover their tracks with item history trackers such as backpack.tf in TF2 or csgo.exchange in CS:GO.
- Beware of brand new accounts, or purchased accounts. Scammers are notorious for making new accounts each time they get banned. You can report them to SteamRep, or report them to Valve, but the sad truth is they're already counting on the account getting banned, and they plan to "cash out" or transfer your stolen items to another account long before any of that sets in. Many of them are career criminals who do this for a living, and it's a constant cat and mouse game, but as a consequence scammers have to keep making new accounts so you might be able to recognize a sketchy profile before you're scammed.
- Sometimes scammers buy accounts for their old creation date to look legitimate, but if you look around you can often identify these types of profiles. Check various trading websites for how actively the account is used; is their first trade posting 2 months ago, or 2 years ago? On their SteamRep profile, click the "Historical data" link and look at the dates their profile was viewed and cached; was this account from 2003 first viewed last week, with maybe 1 view a couple years ago, or is there a long list covering over a year? If the account has a really old creation date, but hasn't been used for trading until very recently, you should assume it was purchased and treat it the same as a new account.
- Low hours in the game they're trading for, with an unusually deep knowledge of the items and economy for that game. Ask yourself why someone who doesn't even own CS:GO, or who has less than 50 hours, is so interested in your knife. Does this level of high value trading seem logical for a newbie to understand?
- Look at the number of paid games in the account. Scammers love to boost their Steam level to look more legit. A single stolen knife will often more than cover the cost of leveling a profile to 100, but adding a bunch of games requires a more substantial investment, and you can see for yourself whether the games they do have are AAA titles like Elder Scrolls, or a bunch of cheap Indie games costing less than $1 each. An account with over 100 games is less likely to scam you than one with less than 10, but the key here is determining how invested they are in their account. Does it look like something a scammer would be tempted to throw away if it means running with your items, or does the account appear to be worth more than what they'd steal? Useful link for assessing their account's worth: https://steamdb.info/calculator/
- Quickselling newly obtained items, maybe just a couple days old in their backpack according to item trackers. If the deal sounds too good to be true, it probably is, even if everything is in the trade window. Ask yourself why they're in such a hurry to trade this; usually scammers try to quicksell items as quickly as they can before the imminent trade ban, and since the items were stolen anyway they aren't really "losing profit".
TF2 item tracker: http://backpack.tf
CS:GO item tracker: http://csgo.exchange
- Nearly empty backpack except high value items and keys are often a sign that the account is being used for nefarious purposes (less applicable with game trading). Ask yourself if this type of backpack seems logical for a trader.
- If the person you're trading with puts emphasis on fake/worthless reputation such as profile comments, CSGO/DOTA2 Lounge reputation score, or any other "reputation" system that lacks accountability or transparency, you should reconsider whether to trade with them, at all. These forms of "reputation" do not provide any evidence of someone's trustworthiness, and are widely abused by scammers to appear more legitimate than they actually are. No amount of profile comments will negate any of these red flags, and more often than not anyone encouraging you to honor them, or vaguely citing rules about "who goes first" because of them, will try to scam you. We highly recommend reading this guide on what constitutes reputation.
- High Steam Level or expensive backpack does not mean reputable. As an added note to the above point on reputation, many scammers will approach you with a high Steam level, and try to assert that as a sign they are trustworthy. A single stolen knife can easily pay for leveling a profile up past 100, and scammers see it as a business investment to put victims at ease. If someone says you can trust them because of the items they have, their experience trading, or because their Steam level is higher than yours, you should avoid trading with them.