As Robert "experimented" Pinkie Pie performed just as he thought she would, her head slowly tilted into the other direction. It was a subconscious movement, she was merely trying to follow his eyes and be polite. He was strange, he looked at her the way Twilight Sparkle sometimes looked at her -- like a specimen instead of a pony, or in this case a human being. She gave him a sly smirk, and winked, tilting her head back to normal - just to acknowledge she knew exactly what he was trying to do to her.
When Rosalind agreed with her brother's statement, Pinkie placed a hand on her tiny hips, the other one moving to tap her chin, "Well, you two are the first to have this theory. I haven't heard of it before. Then again, I'm just a churro stand worker and baker - sometimes a party thrower, too, but no one really wants to party here."
When Rosalind said this place would be fine, Pinkie opened the door and stuck her head in, "Well..." She felt apprehensive about this. "If you say so... though, I think it needs more color." She wrinkled her tiny nose in judgement, "Not a lot of color, just something to get rid of the boring grey walls."