For what it's worth, I think I significantly prefer "sorry, I know we've met before, but I've forgotten your name" (with bonus points for 'I remember you from [

For what it's worth, I think I significantly prefer "sorry, I know we've met before, but I've forgotten your name" (with bonus points for 'I remember you from [x]'), rather than "hi... [wrong name]?" The first is just straightforwardly honest (and forgetting my name is completely understandable), whereas the second can feel a bit disrespectful, though it's hard for me to analyse exactly why. It's not a big deal, and I've done it myself, but personally I wouldn't recommend guessing unless you're reasonably confident you'll get it right. Mostly I think remembering the person is much more important than remembering the name, anyway. If someone forgets me entirely, that can be hurtful if I remember having an interesting interaction with them. Even if they remember my name, that doesn't mean very much if it soon becomes clear that they don't remember anything from our last conversation. But if you remember me, I don't much care whether you remember my name.