When paid ads experience big jolts/pivots, like an overnight spike in CAC, performance marketers immediately blame the ad algorithms, the creatives, etc. But what I've seen is that these jolts are actually lagging indicators of off-platform brand issues, particularly undetected bot-driven outrage campaigns, and unexpected shifts in what AI search engines (e.g., ChatGPT, Perplexity, etc.) say about the brand during final diligence.
To not be too reactionary, the decision rule I employ is the "Sentiment Anomaly Check".
Before pausing/touching the budget on a historically taut campaign, I recommend cross-referencing the CAC spike with continuous AI sentiment monitoring. If the ad algo drops 48 hours negative, check your social listening/AI response monitoring. If anomaly detection calls out an unnatural spike of negative sentiment (and I know one B2B tech example where this happened and the campaign's conversion rate dropped from 4.2% to 1.1% in a matter of days because genAI tools started pulling from a negative forum thread that got bot amplified), then you simply cut ad spend immediately. You can't be ramping ad budget into a funnel where an undetected AI search narrative is eroding trust. You pause ads, engage in suppression, and pre-bunking.
However, if your real-time AI monitoring tells you the overarching sentiment online, as well as the outputs from AI conversational agents, remains perfectly stable, then the decision rule is to hold. These are usually just normal algo shocks. We hold spend for at least 5-7 days before optimizing.
This is a great example of why the interplay and symbiosis of AI tools with human-based decision-making is so important. AI can crawl real-world datasets at scale to detect these off-platform fires, but a marketer needs to look at the dashboard and realize that a sudden CPA spike is not because of media buys but is actually an algorithmic hallucination that's costing the brand performance. Holding on to the ad algo avoids too much reaction, but data-driven from rapid sentiment makes sure you don't miss a fire.