@mkarpicz, sink.good property denotes loading valid data into Elasticsearch. That includes loading data to both good and bad indexes. You should be able to check your bad data in Elasticsearch/Kibana. You can use this tutorial to query bad data: Debugging bad rows in Elasticsearch and Kibana [tutorial].
As an alternative solution, before sending your events to production pipeline you can test the events with Snowplow Mini.
You send structured events with the pixel (e=se). We gave the vendor name for those events com.google.analytics as we borrowed the idea from Google Analytics.