1. Audience Monitoring: Using influencer marketing platforms like Flinque, regularly analyze the demographic data of the influencer’s audience. Keep an eye on authenticity indicators such as engagement rates, frequently used emojis, and common keywords in comments.

2. Regular Review of Content: Continually review the influencer’s content for consistency, creativity, and adherence to your brand values. This will help ensure the quality and authenticity of their audience.

3. Engagement Metrics: Monitor regularly the rate and type of audience engagement. Authentic influencers interact with their followers and spark discussions, which can lead to higher engagement ratios.

4. Influence over Time: Use a tool like Flinque to track an influencer’s impact on your brand awareness, sentiment, and other important metrics over time. An authentic audience will consistently engage over time.

5. Contractual Clauses: Add clauses to your contracts that require influencers to uphold certain levels of authenticity, such as maintaining a certain level of audience engagement or a positive brand sentiment.

6. Audience Quality Reports: Tools like Flinque offer detailed audience quality reports, which can help you verify the followers of your potential influencer partners before signing contracts.

7. Reduction in Fake Followers: An increase in fake followers can negatively impact the quality of an influencer’s audience. Platforms like Auditor for Instagram provide an estimation of fake followers, giving you an idea about the authenticity of their followers.

Remember, no single approach will fit all scenarios. Depending on your specific needs, capabilities, and resources, the right mix of these strategies will vary. The key is constant monitoring, adjustment, and open communication. Adjust your strategies as needed for each influencer.