He lies constantly. Partly because he's dishonest and only cares about himself and his family's wealth, real or perceived. The other times he just makes shit up because he doesn't know shit about shit so he wings it. Or he regurgitates literal conspiracies / propaganda he hears on Fox News, sometimes verbatim. Literally. Some of the batshit things he tweets can be traced back to a Fox News segment 10 or 15 minutes prior. This is the type of shit we expect from Chuck Woolery or James Woods...not from the President of the fucking United States.
He was a main antagonist with the birther conspiracy. He's used his presidency to undo Obama's legacy for spite. It's deranged.
Scumbag is too polite a descriptor.