Yes they can. You can search the forums for many scammer stories regarding e-bay and bitcoins(litecoins) etc. The most common scam being paypal chargebacks or disputing the charge on thier CC after you transfer the coins to them.
Pixl8tr
They can't scam you as long as you verify the coins were confirmed. Once coins are sent, there is no going back unless whoever received them decided to send them back.
That's a hard one. PayPal states that people buying and selling BTC is against their TOS, so I'm not sure who they would side with in that case.
http://www.redstate.com/schoolofprivacy/2013/04/24/paypal-soon-to-accept-bitcoins/
fascinating