Why are there always aggressive dogs or bad owners at the dog park?

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
   Avoiding dog parks entirely, especially with small dogs
2. 2
   Using a leg or knee to block a jumping dog
3. 3
   Preventing bad situations rather than trying to control them
4. 4
   Using a Y-shaped front-clip harness
5. 5
   Practicing red light, green light stopping techniques
6. 6
   Using a flirt pole in the yard
7. 7
   Using a long line in a field
8. 8
   Making walks sniffy instead of a march
9. 9
   Curving out when approaching other dogs

In their words

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