I nearly got caught out as well , when you type esta into google the first site I got up wanted to charge $495 dollars to fill in the form for me
I personally can't believe that the online process checks anything. My clearance came back within seconds. I don't think the form asks the right questions anyway, basically its name and passport number and a load of questions that no one in their right mind will answer yes to!
You'd think that just from my date of birth the system could figure out that there is no way I could have been a member of the nazi party in the 40s!
Still it didn't ask for my maiden name , this being the root of my potential problems , so I'm happy
