That's a fairly noisy data source with lots of both false positives and false negatives.

I've actually been burned by use of that data as a user - the last time I was in Germany for a CCC camp, I needed to log into my bank account. Not trusting the WiFi, I bounced through my VPS to do so. It seemed to work fine, but a few days later the bank froze my account. When I called them they insisted that this activity meant my computer and email had been hacked and I needed to change my email password, virus scan my computer, change my username with the bank and change my password. There was no way for them to mark the use as 'legitimate'.

On the other side of the coin, there are lots of ad fraud bots running through residential ISPs.

what? ARIN tracks all American IPs (thus the 'a') - but if you are a residential ISP, you also get your IPs from ARIN. But the point is that you can't go to ARIN if you want information about European IPs; RIPE is the equivalent European org.

If an IP isn't allocated by a RIR, it is a "bogon" and usually dropped by your anti-spoof filters at your router.

Interesting idea.