So, I've been wondering about this for a while now.
A lot of people cannot quit stressing how important it is to clean and sanitize everything, to the point where I'm starting to experience their concerns as a phobia rather than rational precautions.
One thing in particular bothers me: the fear of contaminating beer after primary fermentation. At that point, most of the substrate that micro organisms can feed on (simple sugars, organic phosphates) has been depleted, and replaced with alcohol which will kill most contaminants.
If a foreign lifeform where to end up in the beer, survives the alcohol and didn't starve to death, it still has to compete with the yeast still present. Billions upon billions of yeast cells to compete with mere thousands of contaminants. Competing for example for whatever oxygen is present which could go to turning alcohol into acetic acid.
So bottem line: has anyone ever had a contamination after primary fermentation?