The answer to your question is here: http://www.question2answer.org/qa/28769?show=28769#q28769
In a recent commit a function was implemented to remove those characters from the core.
If you are not using MySQL 5.5.3+ or maybe you don't want to change your database structure you might also consider switching those characters to HTML before storing them. E.G.: 😁. A filter module should do the trick.
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