Could FB do something like this to detect click fraud/misbehavior: FB's ad system only counts a click as valid and charges the advertiser when the browser from which the click originated has js enabled.
OP says only 1-2% of users have js disabled hence FB would only miss out on a relatively small amount of ad revenue instead of massively over-charging.
OP says only 1-2% of users have js disabled hence FB would only miss out on a relatively small amount of ad revenue instead of massively over-charging.