Social proof is the idea that people look to the behaviour and opinions of others to decide what to trust. Reviews, follower counts, testimonials, and comments all act as social proof: if other people seem happy, a new prospect is more willing to take the risk.
On a paid Facebook or Instagram ad, the comment section is the most visible social proof you have, and it updates in real time. New viewers read the comments before they decide whether to click or buy. That makes it a powerful asset — and a liability if it is left unmoderated.
Spam, scam links, and angry pile-ons sitting under your creative send the opposite signal: that the brand is careless, or that the offer is not to be trusted. Because the ad is putting that comment section in front of a cold, paid audience, the damage is amplified — it can lower click-through and conversion and, in turn, push up your cost per result.
Moderating ad comments protects social proof by keeping the visible thread honest: hide the spam, remove the abuse, and never bury a genuine buyer-intent comment. ROAS Shield automates that hide-or-surface decision over Meta's official Graph API. For the wider context, see ad comment moderation and reducing cost per result with comment moderation.