Wild yeasty stuff goes better in a natural environment. I've found it easier once I moved out of town and into the country. It's more natural and literally in the air around us.
There's a nice story about a familybrewery nearby that made a pale wheatbeer with part
wild fermentation. A big brew-corp bought the familybrewery and recipe, decided to take the recipes and fermentation cultures and move production to their own big facilities 100 km further. They couldn't get the flavour just right, no matter what they tried. Sales started to drop and they eventually reinstated the familybrewery, with the familymembers as managers, in the old facility and lo and behold, the flavours were back. It turned out that the specific cultures were somehow ingrained in the air at the old place (scenic town, lots of clean air). The new factorybrewery was near a crowded
city, closer to sea and on industrial premises. Even when the rest of the process was the same to the uhmpth degree, the results weren't.
I start sourdough for the first time with a dried sourdoughculture from the healthfoodstore and then keep that going. It makes live easier, you learn when the dough is still okay or
should be tossed and it builds confidance. Getting some dough from a nearby natural baker or fellow-permie would do the trick too I suppose.
I've got my first batch of sauerkraut going right now. I've used some sauerkrautjuice from bought sauerkraut to get things started. Green, hairy, stinky is not good... A bit of white scum is okay though.
Botulism is a danger especially with canning gone wrong. On the other hand, people have survived until now with amateur canning and other experimental conservationtechniques, so you problably shouldn't worry.
When in doubt, ask your pets for advise: If my cat doesn't want to eat a suspicious piece of meat, I dispose of it. If the
rabbits or dogs don't like the veggies, same thing. If they like it and it tastes okay to you, it's problably okay.