I consider myself a pretty easy going person. I don't get my feathers ruffled easily. So why should I care so much about the use of this word? I cringe every time I see it used incorrectly. It's actually pretty simple to get straight. If you can say "you are" in a sentence then you must use you're, not your. The word your shows ownership and simply doesn't work for this sign, unless it read "Your smile is on camera". That would have worked. I saw this sign at a professional establishment and was surprised that even the company who was hired to make the sign couldn't get it right. What is up with that?
Okay, my feathers are calm now. Have a delightful day.