A lot of his points sound like he's reaching for low-hanging fruit that every other major news network has juiced for a headline.
For example, his response about the David Duke endorsement. He claims Donald Trump is a racist for responding to a news anchor in the way he did. Anyone can endorse Trump for whatever reason they want. He doesn't control that, and quite frankly he doesn't have to make some statement claiming he doesn't want their vote. That's exactly the kind of politically correct garbage Trump (and his supporters) don't care about. Because he won't publically claim that he doesn't want the vote of someone who is a racist means he's racist? That's very stupid. News flash for Oliver, in America people are actually given the freedom to be racist! It may not be a pretty thing, but it doesn't mean that Trump has to panic and apologize because a racist endorsed him.
Then, his statement about Trump's multiple failed business. I'm not sure how often he interviews entrepreneurs like Trump. A business failing has nothing to do with a campaign. People take risks on businesses. This guy has been involved in such a wide range of businesses that I think it's pretty clear that, at one point, he was throwing ideas at a wall and seeing what stuck. The dude has gone from real estate to side businesses like steak and vodka... Does John Oliver not think Donald Trump knows the risks of starting a business? A "failed" business isn't entirely a failure when you understand and accept the risks you're getting into. Taking chances is how you become successful. Trump is loaded right now, so how much of a failure can his businesses really be? Is Oliver under the impression that the other candidates have never failed at anything?