I recently did a couple of tests with paid advertisement through buysellads. Actually it was not for a startup but for some affiliate link (Udemy courses with g

I recently did a couple of tests with paid advertisement through buysellads. Actually it was not for a startup but for some affiliate link (Udemy courses with good discounts) and the result I got was very bad: - a generic Udemy ad on a generic site: 10k impressions, 11 clicks, 0 conversion - a specific course advertised on a niche newsletter: 1800 impressions, 15 clicks, 0 conversion And for conversions I mean neither a sale nor a new signup into the system.