im on a server where there is also that problem.
what i did was kick ban the user when he join that has done the trick for a while.
now what he or she is doing is join part channel and get nicks who iare in the channel and then msg them.with that msg.
its always a nick like example: `]{a[ , ]`aw{ , }]c ,`a[ etc.. random letters and charactors.
i have tryed the bogus thing in eggdrop.
set kick-bogus 1
for bogus nicks but not effective
i dont know if that set kick-bogus 1 is al you have to do to active that bogus thing ??