If they have any reasons to suspect that you will get deported as soon as you step on the destination. They will not allow you to board the plane. If they take a chance to let you fly and on arrival you get deported. They will have to pay a big fine. Therefor the airline dont take a chance.
I am a travel agent and I have seen few times that airlines deny boarding if they dont believe you are a genuine tourist or have a reason to believe that you may over stay your visa. Dont think they have black list database though.