If they were honest they would say something on the order of "I like his positions on immigration and trade, and am willing to put up with everything else for the sake of those issues."
In fact, many people who support Trump disagree with him on a variety of issues. I will support anyone but Jeb Bush and I completely disagree with Trump on Eminent Domain. I’d like to see his feet held to the fire over this. On the other hand, he has many positions I support and he’s magic on the platform. Funny, down-to-earth and real. That’s what’s attracting people.