Cause: bacterial growth
Symptoms: persistent "fermentation" (aka bubbling in the airlock), even far past the window it should happen, a weird sour apple smell out of the airlock.
- Percent sugar recorded at ~3% by hydrometer after almost two weeks with consistent bubbling implies a "gusher infection" per How to Brew
- That sour lambic smell that shouldn't happen in a holiday ale.
- Wort tasted and confirmed un-sugary and un-alcoholy. And just plain wrong. Yes, I drank bacterially-contaminated wort.
- Sanitize equipment better (we used unsanitized equipment to squeeze the hops bags outside the acceptable temperature range to do such a thing, and I can think of a couple other things we could sanitize better)
- Sanitize hands (hand sanitizer purchased)
- Take a specific gravity reading so I can earlier test when something seems wrong and pull the plug earlier, with more confidence.