[nznog] How common is unfiltered BGP?

Hi everyone, I'm just updating my lecture on exteriour routing for this year, and am wanting to know more about the current state of unfiltered BGP, whereby a customer can advertise a prefix they don't have, their service provider didn't suitably filter the advertisement, and it disrupts other networks in the internet. My previous impression, based on discussions around incidents such as the YouTube/Pakistan incident, lead to me believe "Most people don't filter", and I'm just wanting to see if that is [still] the case now. (Also, thanks to Andy for the NRO nudge) Cheers, Cameron