the fun part is watching the bgp announce/withdraws in unallocated space. (no matter what microsoft may have learned from their survey, most isp's don't seem to care which prefixes their bgp-speaking customers advertise.)
So which ISPs are confused? Bogon's don't spontaneously occur in BGP. Some ASN must originate them, and ASNs must pass them to other ASNs. BGP helpfully includes the ASNs in the path.
geoff huston is the only person i know who's making formal progress on that question. i know from some zebra log files that iana's unallocated space gets advertised from time to time, then withdrawn. presumably an attack was launched during the announcement but i don't have any data showing this.
What should be done about ASNs which repeatedly announce false or unauthorized routes?
apparently, nothing. to the extent that peering is by agreement, the majority of such agreements now in force do not require the other party to route-filter their customers. which is funny, since they tend to drone on endlessly about the importance of a 24x7 NOC, which in operational practice, matters lots less. (btw, anybody signed a peering agreement which requires an abuse@ mailbox yet?)