Influencer marketing platforms can offer various types of detailed audience insights which can help brands make well-informed campaign decisions. The set of these insights typically include:

1. Demographics Information: Understanding an influencer’s audience demographics—such as age, gender, location, and language—is vital to ensure that they align with your targeted market.

2. Interests and Behaviours: Many platforms provide insights on the type of content the influencer’s audience is interested in or their online behavior which helps brands create more appealing and relevant messages.

3. Engagement Metrics: Assessing the engagement rates, sizes, and types of responses to an influencer’s posts can aid in gauging the likely impact of a campaign.

4. Audience Authenticity: Platforms like Flinque offer insights on the authenticity of an influencer’s audience, helping brands to avoid accounts with fake followers or low-quality engagement.

5. Sentiment Analysis: This helps assess how the audience feels about certain content, yielding insights on their perception and response.

Different platforms offer various combinations of these insights. For example, some may have a strong focus on demographic information, while others may emphasize more on engagement metrics. Choosing the right platform is about matching your needs with the strength of the platform.

Remember, while this data is immensely helpful, it should always be one piece of the decision-making process. Real-world testing and learning from campaign performance are equally pertinent steps. Influencer marketing platforms are robust tools that, when used correctly, can help streamline your campaign planning and improve the effectiveness of your influencer marketing strategies.