auto joiners are scripts/bots that enter GA's without a user needed or only needed for 1 click to enter all GA's on one site . Maybe in cmbination with a endless scrolling script (so you have only 1 site and can enter max. GA's with only 1 click). Not allowed but very much people use such shi*.

Extreme leechers are, from my point of view, people that are as example 3 years+ here and give nothing or only 1 game to be lvl 1 but took hundrets of Games.
Only greedy people, nothing else.

With both "groups" you have after the win problems. You must run behind them that they take the key (WTF), that they set the recieved hook, a thanks is mostly not known and such "basic (manner)" things.
As long as the recieved hook is not set a GA slot is blocked and can't be used for more GA's. That is very bad for new users because they have not really much (i remember me on 3 slots at the start..)

So all in all not really funny with the most people under lvl2