Metrics
Lead quality
The downstream conversion / contact rate of leads sent to an advertiser.
Lead quality is the post-submission performance of leads — answer-rate on phone, qualification-rate, install-rate, sale-rate downstream. Advertisers running CPL offers track this religiously and either scrub fake leads (no payout) or down-tier publishers whose leads don't convert. Weekly QC scrub-rates above 15% will get a publisher kicked off most CPA networks.
Example
Affiliate sending 800 auto-insurance leads/month at $32 CPL — but advertiser's contact-rate is 31% vs network average of 58%. Payout cut to $22 next month.