In all my years as a JW, I have heard of this happening twice.
In the one case I am aware of, the person really didn't care and was a PIMO. Apparently someone who looked like him was spotted by a JW going into a single woman's house at night and told the elders. The elders did the spying stake-out thing and waited in their car and "saw" him go into the house at night. When asked by the elders, he denied it. He was DF'd and did not appeal.
After the fact, and the reality of what was happening with his family, he presented evidence that he was not even in town the night that the elders claim they saw him. He showed evidence that he was traveling to see relatives/vacation in another state. The elders called and confirmed his side of the story. He also had a couple of receipts from things he had purchased hundreds of miles away that weekend when the elders said they saw him near his home.
In the end, an announcement was made something to the effect that the he was no longer disfellowshipped and that any congregation action against him had be rescinded.
He was not in my congregation but in the next town over and it was quite the news for several weeks.
Rub a Dub