I often play operation lockers and most servers have their own "rules". They don´t allow many weapons like m320 or MX25. But there are many cheating admins who just run around with their assault rifle squad and dont allow everything which could kill them. They dont allow shotguns, or even bipod. claymores too. They just run and jump around recive themself and overpower everyone.
Another server was even more creepy. They didnt allow anything like the weapons i mentioned before. But if you pay a VIP slot with real money, you can use them without any limits.
And there are servers who kick you from time to time to make room for others who join. You have to pay a VIP slot to avoid this.
Not to mention the helicopter-lamers-admins who dont allow antiair weapones.