You are 100% responsible for your own trades, both buying and selling.
Please bear in mind anyone can register an account on the forum and post up something they apprently have for sale or apparently want. Check trade feedback, check their post count, check their forum content and so forth. Please do read the stickied posts with advice. However ultimatly it's up to you to decide if you want to risk trading.
Please note that from time to time scammers post replies, typically asking you to phone them because they have whatever you are after. They may do that publically here or they may more often use the private message features. If the latter and you have the slightest doubt please report the message and don't phone them. Typically they may have messaged several users and consequently several reports will soon highlight the behaviour.