I was told it was all random but I changed out of my shorts in to jeans and put on shirt so they where checking fresh washed clothes. They had me empty my pockets , turn them inside out and hold my hands out in front of me. Then they wiped above my pockets front and back around my belt then wiped under my nose. After that they took another swab and wiped just my hands and fingers. I think they are looking for both drugs and explosive traces. The nose wipe tells me they where looking for drugs. Back in the day we use pull up in airport drop off area killing the last sub.