Well, I recently did a simple spell to help someone solve some learning problems. First time I did it for a friend with a great result, this time I didn’t even know the name or what this person looks like.
Still worked, as far as I know. Was using sigils of Uriel and Metatron from Archangels of Magick.
I think - but it only my theory, nothing more - that entities, being sentient and all, can track someone down based on what you know, even if it’s just a nickname on the Internet. But I don’t know if it will work for, say, love magick.