People get very upset when they hear something unpleasant. The truth hurts, by golly.
When Hillary Clinton called out half of Trump supporters as a "basket of deplorables, racists, homophobes, xenophobes etc." there was quite an uproar. Apparently, it is impolitic to call racists, homophobes xenophobes, et.al, what they are. It must hurt their feelings. Clinton backed off, but only on her reckoning of the percentage.
Racists, homophobes, xenophobes and islamophobes all propelled Trump to the Republican presidential nomination. That was clear for all to see, no doubt about it. Deplorable is as deplorable does, when it's the Republican base.
What we are seeing now in the general election, is how deplorable the general electorate of this country is. As Trump narrows the gap, by some polls measurements, it becomes clear that those unaffiliated voters, the "undecideds" (or low information voters) are actually coming close to crowning Trump as the next president.
These people are being persuaded by Trump's cold reading of scripted speeches and posturing. They appear to be completely unaware of the lies and the racism that is the Trump candidacy.
Now THAT, is what's truly deplorable.