Re: "Democrats were a whole lot dirtier this time"
The tragedy of this last election was that the RNC had a plan to stop the real dangerous candidate - Ted Cruz. They had a whole campaign of ads against him, they had journalists briefed, audiences primed, a large troop of great and good ready to cast subtle aspersions on his competence, character and sanity. It was a good plan, and it worked a treat.
They didn't think they needed one to stop Trump.
And why should they? After all, surely the religious right couldn't support him, and anyone who calls themself a "conservative" certainly couldn't. Heck, the man has never even pretended to be anything but a lecherous, corrupt, vacuous, ignorant spendthrift. So he'd be bound to lose the race, right? Worst case, they'd lose the presidency - and they could certainly live with that, so long as they get to keep Congress.
Unfortunately, they underestimated just how mindlessly partisan the base is.