And if the buyer sends me an envelope full of monopoly money??
Doesn't really matter to me what you do. I can only tell you about my experiences on swappa.com. Whether you believe me or not is up to you. Whether or not you can actually trust ANY type of online transaction is up to you. You can ALWAYS say "what if" regardless what I tell you OR whether you are making a transaction with a person or a company. "What if" Amazon sends me a box of rocks when I purchase something else??? What "proof" do I have that I actually received a box of rocks???
There are safeguards in place. If you don't trust them, don't use swappa.com and keep your phone. I don't really care.
Click on the following link to read about what safeguards are in place and what protections you have. As far as I know, Paypal DOES NOT accept Monopoly money for deposits.