The problem happens most commonly if people /quit or /exit, or if they go LD, but I am pretty sure it even has a rare chance to happen if they /camp. On a public server when I was running Windows, I would commonly see up to 15 or more ghosted characters in nexus at any given time of the day if I didn't boot them out manually every few hours or so.
The easiest way to tell 100% if a character is a player ghost is to turn on inspect so you can inspect people "/toggleinspect on" (you can test by inspecting yourself or another player you know isn't a ghost) then try right clicking a suspected ghost player and if the inspect window doesn't pop up, they are sure to be a ghost.
Even after they log off, you will continue to get net error messages from them in the log files. I believe the error that shows up is something like this:
Code:
Tried to write a packet beyond the end of the queue!
The error starts with showing incremented packet numbers, but eventually I think it just shows the same packet number over and over and over. And that error will continue to flood server logs even after the player has logged off and I think even after you #kick the ghosted character. So, it is like a connection isn't being brought down for some reason even if there is no connection. I think I have even had a player reboot their PC and it didn't stop the errors or disconnect the ghosted character. So, to me it seems like the issue may be that the server is just hung in some sort of loop.
More info on that log error can be seen in this post:
http://www.eqemulator.net/forums/sho...light=flooding