How do I evaluate whether a premium video inventory seller is credible and unbiased?

To evaluate whether a premium video inventory seller is credible and unbiased, look at both proof of quality and proof of independence.

1) Check their supply quality

Ask for evidence on:

• Publisher relationships: Are they directly authorized by the publishers, or are they reselling through layers?
• Placement transparency: Can they show where ads run, on what content, and in what formats?
• Inventory type: Is it premium in-stream, out-stream, CTV, or a mix? “Premium” should be defined clearly.
• Viewability and completion rates: Request historical performance by placement.
• Brand safety controls: Ask what categories, keywords, and exclusions they use.
• Fraud prevention: Look for measures against bot traffic, domain spoofing, and IVT.

2) Assess whether they are unbiased

A seller can be credible but still biased if they only push inventory that benefits them most. Check:

• Disclosure of conflicts of interest: Do they own media, represent only certain publishers, or receive preferential economics?
• Selection criteria: How do they decide which publishers or placements are “premium”?
• Comparable alternatives: Do they present multiple options, or only one preferred package?
• Measurement transparency: Do they use independent measurement tools or only their own reporting?
• Optimization incentives: Are they paid on spend, margin, or performance? Incentives can shape recommendations.

3) Verify with independent sources

Use outside validation:

• Third-party verification: IAS, DoubleVerify, MOAT, Pixalate, etc., if applicable.
• Ad specs and policies: Compare claims against publisher or platform documentation.
• Reference checks: Ask for advertiser references or case studies with named verticals.
• Market reputation: Look for consistency across multiple buyers and agencies.

4) Ask the right questions

A credible, unbiased seller should answer clearly:

• What is your direct vs. indirect supply?
• Which publishers own this inventory?
• Can I get log-level reporting or placement-level reporting?
• What is your policy on hidden fees or markups?
• How do you define “premium”?
• What independent verification do you support?
• What inventory would you not recommend for my campaign, and why?

5) Watch for red flags

Be cautious if they:

• Use vague terms like “premium” without definitions
• Refuse to disclose publisher names or placement details
• Overstate exclusivity or guarantee results without data
• Only provide their own dashboards and no third-party verification
• Push a one-size-fits-all package
• Avoid discussing make-goods, refunds, or underdelivery policies

6) Run a test

Before committing:

• Start with a small pilot
• Set clear KPIs: viewability, completion rate, CTR, brand safety, attention, conversions
• Compare against another vendor or benchmark
• Review results at the placement level, not just aggregate

Simple credibility scorecard

Rate each 1–5:

• Direct publisher authorization
• Transparency of placements
• Independent verification support
• Brand safety/fraud controls
• Disclosure of conflicts
• Consistency of performance data
• Willingness to answer tough questions

A seller scoring high across all categories is more likely to be both credible and unbiased.

If you want, I can turn this into a vendor due diligence checklist or a questionnaire you can send to sellers.