Click farms (via vpns), bot swarms, etc. I wonder who would still trust such 'clicks' metrics. Wild guess, in the context of selling "something" and using ads

Click farms (via vpns), bot swarms, etc. I wonder who would still trust such 'clicks' metrics. Wild guess, in the context of selling "something" and using ads on the web, the only reliable metric is the correlation between the sales amount and the ad campaign.