Suggestions: Wiki/Sticky/Guide: "How to fix it"

I live by the rules, never throw food, you can always make something good out of it.
And if it's beer, no one wants to see their hours of hard work and weeks of anticipation in the sink if they can help it (or drink it ).

Can we have a sticky / wiki for the classics instead of opening a new thread every-time? It would also be helpful to know what really works best.

For example:
Fermentation stopped in the middle
Infections
Taste issues
Low/high alcohol

 

You lost me....