I recently rolled out a whitelist and I'm using the wallet for accounts to get started.
While I was writing the code, I'm specifically looking for "whitelist" and I was thinking what to do if I receive something else and so I just wrote some code to return the transfer with a memo that was just a goofy development placeholder that I intended to change later.
And then I deployed it to production.
I noticed this and literally laughed out loud! It became clear that this account understood what I was getting at, since a new transfer came in moments later.
Sometimes my placeholders are a bit more crude and since this was kind of humorous I thought I'd just leave it. I had completely forgotten about the wonderful transfer memo spammers until this came in.
I'm serious, as much as I'd like to hold on to that fraction of a cent, it's so much more satisfying to reply to this nonsense with an unbearably appropriate, "Huh?"
Once again, I think I'm just gonna leave it.