Can an adopted puppy suddenly turn aggressive even with proper training?

What people tried

Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.

1. 1
   Reading stories and situations online
2. 2
   Setting up strict ground rules
3. 3
   Planning for immediate socialization and discipline
4. 4
   Throwing a treat to get the puppy to let go
5. 5
   Hiring a professional dog trainer
6. 6
   Returning the dog to the breeder
7. 7
   Screaming when bitten to simulate pain

In their words

Unedited, grouped by where they were said, most upvoted first within each place, each linked to the thread it came from.