When you watch President Obama deny foreknowledge of the latest White House embarrassment, it is obvious why he blew his last window-washing gig.

True to his career goal — to be remembered as the most inept, least serious American president of the last two centuries — Mr. Obama staggered through his latest public fib like a 50-cent drunk. Even his once-reliable gift for subtly reversing the truth has deserted him as he sways and lurches to the finish line.

A liar frequently exceeds his spacious capacity for truth-twisting. Predictably enough, B. Hussein has coughed in the face of honesty one more time.

Wearing what passes for a liberal straight face, Mr. Obama kicked credulity in the stomach the other day when he told several interviewers that, my garsh, he had no idea Hillary was using a private email ruse.

Thanks to WikiLeaks, we know that Mr. Obama belted truth in the chops again. He did know, probably before she set it up. Mr. O. is the cheaper-by-the-hour fibber that his critics figured out he was nine years ago.

Because his liberal base thinks as achingly slowly as he, Mr. Obama has made a clean getaway from a basket full of scandals that he said he did not know about until reading his favorite left-wing journals.

“The president so routinely appeals to ignorance when asked about damaging news involving his administration, it has become a cliché,” said one commentator.

He listed the following scandals that Mr. Obama said he knew less about than an uneducated Nebraska farmer:

• The Fast and Furious gun-walking into Mexico
• NSA spying on foreign leaders
• Gen. David Petraeus’s leak of sensitive information to a woman with whom he was having an affair
• The IRS scandal
• The VA scandal
• The Justice Dept.’s monitoring of journalists.