A snapshot of the verification test requiring customers to click all the vases and elephants in the pictures. [Photo from web]

With low-pixel, fuzzy images people can only identify the color and shape of objects rather than know exactly what they are.

When questions become harder and users need double the time to try and identify objects - "Click all the XXX and XXX" - the chances of securing a ticket dive to near zero as those to popular destinations could sell out in seconds.

Since customers can only make a purchase after clicking all the right pictures, any wrong answers or refreshing of the web page to get easier questions may cost the chance to get a ticket.

Clearly frustrated, buyers found plenty of allies online who have suffered similarly. Some Internet users edited the verification pictures to ironically mock the system for failing to do the job.

They created fake questions including "click all the pictures of handsome men", "all cartoon characters who are short" and "all pictures of the straits of the Bosporus" to show how absurd the questions could be.