As has been said already, it's just a bad combination of a lot of things on one item that make it bad.
Several of those factors include the fact that for the type of item it is the JG's who would want to build it are heavy ganking junglers not counter jungling types.
It takes a considerable time investment. It's also risky to counter jungle, and the item incentives counter jungling just to get the item going (much like Kindred marks) and the enemy team can see that you built it adding to that risk.
Also, the items it builds into aren't the type of things you would want to pick up as first buys (typically), so by the time around mid game when you may want one of those items there is no point in getting the poachers dirk anymore.
If they really want to make counter jungling a big thing then they need an item which makes it slightly safer and gives more gold/exp for clearing an enemy camp as compared to your own. Like, an extra ward that alerts you when people walk past it but are visible to the enemy team or a trap you can set that when stepped on gives you vision of the enemy for 10 seconds.
Poachers dirk just doesn't cut it. Get it? Because it's a knife. : )