Answer first
The biggest SEO agency red flags are ranking promises without money-back terms in writing, no verification methodology, secret proprietary tactics, outsourced fulfillment, no AI search capability, vanity-metric reporting, and long contracts with no performance language. Any one of these predicts a bad engagement.
The list, and why each matters:
- Ranking promises with no money-back terms in writing. Confidence is fine; unbacked promises are marketing. If they are sure, they can guarantee it contractually.
- No verification methodology. Ask how you will independently confirm results. If the answer is their own dashboard, keep looking.
- Secret sauce. Legitimate agencies explain their methods. Secrecy usually hides either nothing or tactics that can get you penalized.
- Outsourced or white-labeled fulfillment. You are hiring a sales layer over an unknown vendor. Ask who actually does the work and where.
- No AI search answer. With AI answers absorbing clicks and organic traffic down roughly a third since late 2025, an agency with no ChatGPT, Gemini, or Perplexity strategy is selling you 2019.
- Vanity reporting. Impressions and keyword movements are not bookings. Demand revenue-adjacent metrics.
- Long lock-ins with no performance terms. Contract length should follow results, not precede them.
One red flag deserves questions. Three deserve a pass.