I was looking at some of the transactions being sent to Poloniex and Bittrex and I see an alarming number of users sending the wrong memo or even no memo to those exchanges, which could result in permanent lost of their Steem or Steem Dollars.
So just to be clear...
Dont send your public key as memo, use the memo provided by the exchange when you click on "deposit"
Don´t leave your memo field blank and whatever you do please DO NOT PASTE YOUR PRIVATE KEY ON THE MEMO, remember the memos are public and everyone can see it, yes that means you SHOULD CHANGE YOUR KEY NOW @toxichan
If you do put in the wrong memo you can contact the exchange 's support and wait for it to be restored but there is no guarantee you will get it back since they explicitly state that they are not to be held responsable if you put in the wrong memo.