On our Foundry devices we were filtering our outgoing BGP announcements not just on a prefix list, but also with an AS regex, to make sure we'd never send out something bad by mistake. On our Juniper routers, we've only used a prefix list so far.
Last week I had a fun issue with a BGP aggregate getting generated by a PyBal LVS service IP. This made the AS path of the aggregate change from AS14907 to AS64600, and this got announced to TiNet in ulsfo (and ulsfo dropped off the net). If we put AS regex filtering in, we can prevent that.