Is it ethical to post fake picture of yourself when talking to strangers?

I'm using an app called Skout on my iPhone. I was there for fun and to practice a language that I need to work on. However, the guys kept on asking me for photos, so I posted a fake picture to protect my privacy. The picture may be found on the Internet, so what if they find out?

No problem, in fact very sensible as long as the intent is to protect yourself and not take advantage of them or exploit their interest, try some reverse psychology and put the ugliest picture you can find and see how long their interest lasts

Why would you care if they found out if this was for your language…