Yobit is surely a scam.  Though I have never done any trade on this exchange, I found out that they are a scam when I was trying to sign up for an account there.  When I tried to sign up with my email address e.g. john.smith@gmail.com, I got an error notification saying that my email address is invalid because it has a "dot" and I have to use another email address.  So, I contacted the support using the chat feature and they asked me to send some 0.01BTC so that they can rectify the problem.

I'm sure they need money to pay the developers to design the product and solve the bugs but when they asked newcomers to pay for this to work, this is something not right.  In the first place, they will get all the trading fees when newcomers sign up and trade on their exchange.

Avoid this exchange in case of HIV.