-Not paying attention to some events (leaving some events with useless drops)
-Making F.O Anc, F.O Socket (the most broken thing mu online history that makes events, in game drops and normal F.O useless)
-Making unbalanced PVP (PVP was always one of the best things in mu online to do, but many servers don't have good PVP balance)
-Offexp, offlevel,offattack (Why making players play in your server when they are offline? and most annoying part is NO FREE SPOTS! Example here is MuLegend)
-Not having antihack
-Launching server only for donate (The best idea is to launch a server where you'd like to play yourself)
-Opening sub servers,closing,opening (Many servers mostly in these days are launching new servers, and closing older ones, for example they have 500x server, they make 100x server, then 10x server, and 500x server closes, then making 5000x server and then 100x server closes)