@cephalophor they call me the roosecat necro expert so allow me to elaborate🚬
aside from the fact that I, tumblr dot com user bastardofharrenhal, think it would've been hot and scary, I also think it'd make sense when we consider that 1) Catelyn was naked when her body was dragged out of the river by Nymeria, 2) Roose has shown consistent interest in Catelyn and 3) Catelyn's death (and the whole Red Wedding) was a humiliation ritual for house Stark and house Tully
the first point doesn't need much elaboration; Catelyn was just naked, bruised and bloody, her corpse bloated from water and throat gaping. You could assume her clothes were taken to pawn off by house Frey, but they'd be bloody. This much more ties with point three.
Roose's interest in Catelyn has a few readings though. One is that Roose was attempting to win Catelyn's favor because the original plan was for her to be taken a hostage. Perhaps he planned to use some of that good will to sway her towards him? After all, Roose never planned to take the fall for the RW, that was all house Frey and Lannister. The plan soured, however, when Catelyn "lost her wits" and the Freys took the liberty to slit her throat. I'd also like it noted that Catelyn does not know who kills Robb, though the reader can figure that out. Roose could've claimed it was someone else donning his armor, that it was not him, etc. The second one is more straight forward: Roose just liked her. Catelyn repeatedly shows a similar volatility towards people while defending herself and her children (the Cat's Paw, the mountain clans of the Vale, Cersei Lannister, even Aegon Frey.) She's not called a she-wolf by Tyrion for no reason. While Roose's angers and appetites are more discreet in public, he still understands her well enough to gift her the skin of Theon's thumb.
And lastly, the humiliation aspect of it all. Both house Frey and Bolton are foils to their lieges; the Freys have an extensive history of resentment towards the other riverlords (Walder Frey himself disdains lord Hoster Tully specifically for a multitude of reasons.) and the Boltons have been feuding with house Stark for generations. After all, house Stark subjugated them once upon a time, long before Aegon the Dragon landed on Westeros. And in the Red Wedding, they finally get that revenge. This was not a losing war, the North wasn't in an amazing position, but neither Walder Frey nor Roose Bolton had strong reasons to side against them, especially not if they retreated into the North and fought a gruella based war, or even met the Lannisters in Moat Cailin. It was that lingering anger that's been bubbling for years that pushed them.
And consider Robb Stark, for a moment. His death was humiliation. Both Robb's and Grey Wind's heads were cut off, and his wolf's head was sewn to his neck and crowned, paraded through the Twins after the slaughter. There was not an aspect of dignity to it. The same can be said for Catelyn. Her funeral was a mock of the Tully funeral traditions we've seen earlier on with Hoster Tully. While her father was let into the rivers armed in his splendid armor, his weapons resting by his side, his boat only sinking when the flaming arrow hit it, Catelyn's funeral was the opposite; she was stripped naked, undignified, thrown from the Twins and into the river with no armor to shield her and no weapons to hold. And to deny that some part of it wasn't because she's a woman would be disingenuous. Even Robb died clothed. Catelyn did not. Its not a stretch to say that something else could've happened to her body. I certainly don't hold Roose Bolton above it. So long as his participation is unknown, he seems rather keen to satisfy himself. (E.G. the Miller's wife.)
There's also the aspect of Catelyn as Lady Stark, Ned Stark's wife, the mother to his heirs, the mother to house Stark in a way. The last one Roose could get his hands on. I think it speaks for itself.
TLDR: it'd be hot and scary i reckon.
