We often see NPS responses that customers think they didn't get a response from us. It's true that we don't reply in every topic, but we do mark an answer and like it to show our face/presence. But still it is not clear to everyone that we're there and approve of that best answer.

What can be done to make it more visible for users that it was an answer we marked? We thought about adding a stamp or watermark to the best answer, maybe as a background image. Or an option to add it via Control, in a simular way a reply can be Marked as Highlight; 'Mark as Approved' or something.

I was looking for different fora to see examples of it, but it looks like it doen's exist (yet). I tried to mock up an example of a reply with a stamp on it, but my graphic skills are not there 

It could also be related to this older idea: 

Though the TS sometimes marks it aswell, but then the Mark as Approved helps.