Did NOT know this board existed, so I am very excited to hopefully get some help!!
We have a male Collie-cross who is 3 years old. He has always been extremely obsessed with 'intimate' human areas, both front and back, mainly belonging to females!
This involves sniffing constantly!!! And if we would allow him to carry on he would lick as well 
we know this from when DD was small and couldn't tell him to stop!
He also has an obsession with used underwear.
God, he's a right sex pest isn't he?!!
Anyone able to help us pretty please???