They are not rare. Rare tags are ones when you look at them you know the meaning without even looking in a dictionary.
PLUS they usually are words. EXAMPLE:
Then there are pop culture og like: Homer Simpson, SNL, Peter Griffin.
Yep haha I did that ages ago and got the same consequences, whats funny though is MS blacklisted the tag I was selling. I had "Scientist" and they just deleted it from XBL, it doesn't exist and cannot be re-created lol.