Bogon list

Tweaking our Looking Glass software by itself would not fix the problem
(ours doesn't have this problem anyway). To fix the problem everyone
would have to tweak their Looking Glass software since the problem can
be seen when someone traceroutes from a peer or 3rd party's Looking
Glass into our customer (in the event they weren't receiving the IXP
blocks from us).

You sort-of want to convince nth parties to launch their traceroutes
_from_ your looking glass, rather than from random places.

Targeting people who look up mappings, you could
always emit pointers to would-be tracerouters -- get yer real
data at http://…

Points to the person who first puts such a thing into the DNS.

One better might be to have the Looking Glass participating routers
manipulate their source IP address for pings and traceroutes.

Yes, this is a good idea.