>>what size scratch are we talking here? seems to me that it would have to be pretty deep to be able to hide contaminants from soap/water/star san.
I don't think thats the case, the scratch just needs to be a lot deeper than bacteria, which is small. It doesn't have to be a deep gauge. Once the bacteria form the biofilm they are very hard to get out, even with chemicals. Thats why hospitals have problems with infections.
>> the reason i say it's a myth is because it is often repeated but in very vague terms as something that is not worth risking. when you look a new brewer posts they very often worry about a scrubbie they used or a scratch they felt with their hand, and so on. so the distinction i'm trying to make is between the scratches that are found in virtually all new plastic fermentors and a real, deep gouge.
of course this is really a discussion that has no end, most people want to feel that they are taking the best care in sanitation so the scratch thing stays alive and it does make sense that tiny bugs can hide in tiny spaces. i guess i look at the other side of the equation; water/soap/star san can get into tiny spaces too.
I wouldn't throw away equipment that had some scratches. But it can make it hard to clean and if it does get infected, it might not be possible to fully get rid of the infection.
>>water/soap/star san can get into tiny spaces too.
Absolutely, but with biofilms it's possible that bacteria can survive that. No guarantees, but it's possible, and can cause reinfections.