Trust me, I know that it's hard to find examples of good apologies! I really tried! One that comes to mind is when Lorde, the singer/songwriter, posted a photo of a bathtub to Instagram with Whitney Houston lyrics in the caption. She later deleted the post and put out a statement apologizing, in which she said, "Extremely extremely poorly chosen quote," she wrote. "I'm so sorry for offending anyone — I hadn't even put this together I was just excited to take a bath. I'm an idiot. Love Whitney forever and ever. Sorry again."
The key here is that she took responsibility, acknowledged that she likely offended people, and apologized.