I just don't use usps, always ups. It's nobody's fault, but I would probably paypal him the difference for the ruined guides. If nothing else, you have a reputation to worry about.
Edit: I've completed about 50 trades online, with more pending.
WANT:
Armored Core 4
Tenchu Z
FEAR
NFL Blitz
NBA Street Homecourt
Wii/360 Points
HAVE:
Crackdown w/ Halo 3 Beta
Enchanted Arms
Kameo
MS Wireless Keyboard and Mouse elite/executive
128mb Memory Stick Duo
SNES games - many rare and in great condition