It's about the 3 letter name: cLl
It's not really a word (it is an abreviaton for a form of cancer tho >.<) but well why i wonder if it's rare is because if you write it like this:

cLl

it is in the shape of a cup

 

it looks rare as 3 letters are ususally concidered rare

 

What's not Rare?


1. Three(3) Character Names – It’s going to be a very long time before these get rare. Ex of a 3 letter: H6L or Q9a. Don’t be fooled when someone says selling Rare Names and it’s a page of 3 letters. There are thousands of combinations for 3 letters. Only exceptions of a rare 3 letter are: words, abbreviations, and ones with a space between them ex: “X D” or triple pairs ex: “555”


This is what i read in a thread

 

This is not considered rare without meaning or a word.