Three of the four (all but Trump) are putatively Catholic. 
When Giuliani was launching into a tirade about Bill Clinton's sexual misconduct on Meet the Press, echoing Trump's suggestion (with no evidence) that Hillary was not a faithful wife, Chuck Todd challenged Giuliani. The exchange went like this:
<<But, Todd responded, "You have your own infidelity charge." 
"Well, everybody does," Giuliani said. "And I'm a Roman Catholic, and I confess those things to my priest.">>
So ... infidelity is ok for Catholics, by Giuliani's lights, as long as they confess. This is an anti-Catholic canard I remember from my youth: You Catholics can do anything you want as long as you tell the priest on Saturday. If a Democratic politician had said this, +Chaput and the Republican Bishops' Conference would have been up in arms. But the 'pro-family' crowd let Giuliani get away with it. Deplorable.