I'd put it at >20% data to be an issue, not 20% users. If generated data was realistic enough (way more than it currently is), even 1% of users should be more t

I'd put it at >20% data to be an issue, not 20% users. If generated data was realistic enough (way more than it currently is), even 1% of users should be more than enough to generate say 50% garbage clicks and data.