3rd Party Software

Recently, someone in FFXI told me that if another player in your vicinity is using "bad" 3rd-Party software, if will cause lag spikes and potentially force you to disconnect from the server.

I know a lot of players use 3rd-Party programs for various purposes, but I don't use any, nor do I really know much about them. I also have no idea what would make a 3rd-Party program a "bad" one compared to a "good" one.

Can anyone shed some light on this for me?
Is it true that other players' 3rd-Party programs can cause your connection to lag, or even disconnect? Or was my source blowing smoke?
If it is true, which 3rd-Party programs are the "bad" ones in question?

There are ways to cause someone to d/c from running into/checking/etc a person but I don't believe that the majority of 3rd-party programs cause this. The difference between "good and "bad" is a matter of perspective, though. Things like Windower and AbysseaWatch tend to be looked as "good" while some bots and hacks still have a negative view from a lot of the community.

Almost every third party app is client-side only because anything that sends information to the server is more easily detected by SE and can be used to promptly ban you. A couple months ago a lazy friend speedhacked to get to a KSNM zone faster for a BB item run and very shortly after he started to speedhack he was automatically teleported to GM jail. Not saying they detect everything, but they do detect some stuff. Using third party programs that send information to the server (besides certain bots and scripts) in general is a stupid thing to do.

Most programs do little more than read and display information in the memory that SE doesn't want you to see ingame: hidden mob health bars, party members' TP, hidden locations of antlions, etc.

i don't know too much on this topic either... but if this is true i'd imagine the programs that have this sort of affect are ones that affect the game itself (i.e. not windower, which only uses some plugins on the players side) so... maybe in game hacks type stuff? like bots... at least those are my thoughts on it