I’m one of them who says that...

In fact, I have recently posted an Ad and clearly mentioned "Serious Buyers Only...".
Few minutes later received a text offering a way below the actual price.
I have replied, "You cannot be serious...?", “I am serious and added 500QR to his offer..!!!” amazingly he replied back.

And that is why we say: "Only Serious Buyers please? Not a "time wasters"....