I'm amazed this thread is still of interest (I'm the Original Poster)Everyone loves shit and customs in the same sentence ha haIf nobody has already, you should really check out National Geographic Channel's Border Security and To Catch a Smuggler shows.They reveal in detail how they look for drugs. They showed a worker in front of an ex-ray machine and postal packages being fed into it one by one. He clearly skipped the letter size packages and focused on the bigger packages. They find everything that is bulk and then do a controlled delivery/  and anything under a certain size (I'm guessing 1 oz) they send a letter to the reciever and then destroy the package. They do scan the small ones sometimes peeps . . . it looked like a miserable job though. Although there really isn't that many packages going across the border. You could spot a vendor's package type and zero in on a vendor after a while if they use the same packaging materials. There are about three large bins of packages to the inspected from each flight. You could see how a express-post packaging purchased from the post office and letter sized, would slip by easily. Its the odd packages and the ones that are hand wrapped that really stand out. It has to look commercial and business-like.One example is a sealed container of vitamins being imported. Once they opened it up for a closer look, they could see the vitamins looked kinda like pills. They tested it and it was all Xanax. They can test everything on the spot.Another factor is that they swab the outside of the packages for traces of drugs. Then, that flags it for closer inspection/x ray. Something to think about when vendors are handling packages.. ...Alternatively, I wonder if adding a few hundred dollar bills to your package would help get it across the border?