Well I know they are not actually spamming the chat but they still should not be there. If each kick is investigated, at least GMs can ban these accounts or some actions can be taken. It is actually quite easy to differentiate a player from a bot, if you are a Mentor, chances are you can tell a bot from a Roe name :P Also, on Cerberus EU, many bots are in FCs name, FCs such as HjjkLa <fT> (random example) so that makes our job of identifying them even easier.
Basically, you are looking for people in such FCs, with names like Qqjkfkak Lfrttakjva, always at Twin Adders GC, always as a BLM/BRD, in dungeon or in group.
Also, not letting such bots take up half the Novice Network is a good idea in my opinion.

And yes, people inviting others randomly without asking is not only a problem because of bots but also because it is rude to just force invite people into a channel without even as much as a "hey", those people often don't even know where they are, what they joined.