Scammers are everywhere. I'm not the dullest bulb in the shed but I have been scammed before! Here are my tips:
#1 NEVER BELIEVE SHOP TITLES when browsing the market, if a shop says 'Glimmer Gems +10' make sure you check the item before you buy it"!
#2 Double check what you are buying is worth that price, check around the market, ask the world or ask a friend! If you're not sure leave it. This also applies to trading with players personally with pets and things.
#3 (I fell for this once) I once paid 3 mil for a good pet only to find that it's life span was at 0, that's right. I bought a dead pet, check the pets health BEFORE buying! It's easy to overlook it when your checking a pets growth and stats.
#4 If somethings too good to be true, the guys probably trying to scam you. Be cautious if someone is being overly enthusiastic, like hes bugging you every minute.
#5 Never get into trading ingots or accounts for your rare items or pets. What will happen is he'll run off with your hard earned stuff, trust me. If he says things like 'Give me your pet and then I'll send the ingots' turn and run. You don't wanna deal with a scammer. Or even 'I'll trade you 1mil now and send you the rest when I have it'. No! Tell him you will wait until he has all the money.