If this is true, then why do the european NAP mailing lists (which push IRR
filtering) have an almost constant stream of "oops, our customer announced
everything to us and we leaked it".
Almost everyone filters customers. The large ISP's all have the
same opinion, if small to medium sized players abuse the system
they get depeered and become someone's customer aggressively filtered.
The large ISP's then trust each other to do that aggressive filtering.
So be careful if you advocate filtering. The IRR, with everyone
doing an update for every customer worldwide does not scale, but
depeering all the smaller peers and letting a few big guys sort it
out does. I don't think that's the result most people pushing