My folks would do that, but they'd take it one step further.
They'd play good cop/bad cop, my dad would really really want the car, my mom would not like it. So they'd argue in front of the salesperson, and my mom would just keep digging in her heels until the price came down a *LOT*.
Then they'd switch roles. Without warning or obvious signal, they'd reverse on the salesperson. Suddenly she's on board, but my dad wouldn't be sure anymore, and not happy about this, or that, or something else, and you know, she made him think about it a bit, and...
The poor salesdroids had no idea what to do, so they just kept going lower. They walked out one time with the sales manager almost in tears trying to satisfy them. When they 'reluctantly' agreed to the deal, he was falling all over himself in gratitude... even though he'd just gotten soaked, badly. Like five figures below sticker, four figures below cost badly.
My dad had been a very successful car salesman way back in the day, and knew every stupid little trick his colleagues would play on the unsuspecting. He quit because he couldn't handle the deceit and dishonesty any more. Flipping it around was highly satisfying to him.
Mom was just kind of evil.