Every time I've needed to pick a lock, it is because I've lost the key, no key, so, lock no good,
hence the bolt croppers,
I will admit to messing with one of the locals where I lived. He used to unlock a padlock to open a gate, hang it on the gate and lock it in place. Later when all finished he would come back, unlock the padlock, and lock the gate with the padlock. I used the coke can shim method to open the padlock and then hung the padlock where he did after he had opened the gate. He would come along the next day and stand there looking at the padlock wondering why it was not where it should be and questioning his sanity...............good sport.