Would Willhuff Tarkin have spared Alderaan if Princess Leia wasn't insulting him?

Of course not.
The whole point was him making her witness the destruction of her homeworld, as an act of asserting dominance over her.
Her betraying the rebels or begging him to spare the planet, would have made the destruction of Alderaan even sweeter for Tarkin.
He knew that, she knew that.
No need for politeness.
This also was not a diplomatic setting.
She was a prisoner.

@ragingloli Thanks for setting me straight.

“Would Willhuff Tarkin have spared Alderaan if Princess Leia wasn’t insulting him?”
– No. Tarkin wasn’t particularly affected by the insult.

“Why does one become a diplomat and lead with the “foul stench” insult, and then expect that he would spare her home planet of Alderaan?”
– She wasn’t on a diplomatic mission to the Death Star. She was captured while trying to get the Death Star plans to the Rebels, as Vader told her he knew when he captured her. She’d been imprisoned and tortured.
– Tarkin seems to have been someone she already had a hostile relationship with before being brought to him on the Death Star.
– I have always assumed that she chose her words carefully and did not think the situation called for politeness, but was expressing her determination despite her position. It’s one approach for handling capture and torture/interrogation situations, to try to demonstrate to the interrogator that there is no point in their continuing to torture them, and/or to upset them so they make mistakes.
– It could also simply be that she hated them so much and saw no reason to hide it at that point.
– She also did not come into the situation expecting him to be such a genocidal maniac that he would destroy an entire planet for no particularly good or sane reason (from her point of view). You can see her mindset change when she realizes that’s what he’s proposing. But by that point, it’s too late.

You can see her mindset change when she realizes that’s what he’s proposing. But by that point, it’s too late.

Exactly my point. I try to keep my insults to myself just in case diplomacy is needed.

The last time I let insults fly the cops where called.

If you want to see the tough strategy work out a bit better in an interrogation situation, you could watch the film I just recommended for its theme song in another thread, The Good, the Bad, and the Ugly. There are many other examples which aren’t coming to mind right now.

When you’re physically helpless, sometimes it’s best if your captors don’t think they can manipulate you.

No. He wouldn’t have moved the Death Star so far if he didn’t intend to destroy Alderaan.