I just noticed one thing that if person have some good drops from the beginning he/she will have such good drops all the time. I guess it works like a random number generation + ID or something. All people who drop hammer or axes also drop gamers, manics, druidics - drop them regularly. Others just have to earn money and buy stuff. As for me I didn't drop anything good since I started to play this game except ghost, spiked green biker helmet and spiked blue biker helmet. No gamer, no bats, no manics but im farming regularly almost since this game started so maybe luck formula not working for all because I know guys who drop manics and gamers every week after spending 1 hour replaying same map.