hounds actually learn to follow crushed vegitation and other traces that are left behind...

(i had police k9 officers put on a demonstration with their K9s for a search and rescue class..thats what they said...YOU dont have to smell..your crushing vegitation, fibers of clothing, rubber from shoes wearing off etc leaves a trail)

i watched one of the K9s follow a trail an hour old, POURING RAIN, across a mowed grass field, through a decint water puddle(not DEEP but water puddled in the grass for 10yds or so) and keep its nose on the track as the track zig zaged in the field...when it lost its straight line it circled and followed it in the right direction like it never lost it...then located the party that layed the trail in the woods after the guy passed through 2 small thickets and 50yds of forest...an hour old track..raining for hours before, the whole hour the track laid, and while the dog tracked...it was amazing...those dogs dont need human scent...