There is no question that the Rotten Belle has great survivability and when with Seamus, two lives. However her natural Df of 6, although suited Crows, it can be easily broken in many cases with a card played from a hand. Pending what Master you're running, Crows could be hard to hold onto and coincidentally may be more valuable than a single stitch on a Belle. Relentless? Two cards is alot. While I can see how it can be usefull in a situation where something needs to get accomplished.. You have to discard two cards and still have a hand that will ensure the Belles success in order to justify the animation. To take a Bench or Tear Apart a Master or trying really hard to confuse something are the only reasons that immediately come to mind as to why a Belle would need to be activated twice.
She can confuse which is great! but a mere Cb 1.. ehh, it may be hard to pull off. And even so there are a number of ways to remove counters. So now we have here a Puppet with the traits of a Tank that can heal and doesn't really present any offensive threat.
I would consider the Belle's role that of an aggressive Work Bench contestor. Run her in, burn her out, repeat. Only ever really expecting to annoy and not do any real damage. Only to distract. A smart player would see this and know that Belles are not a priority target. If one really needs to kill one, there are ways of bursting one down quick without a chance for any of its Abilities to matter.
On Moldy Stuffing, Upon closer inspection I realize that in addition to granting Rotten to a Puppet, it gives it two wounds. Better.. but Masters cant pick it up and it calls for a 7 of Crows in its AD. If I where to make use of this Moldy Stuffing to beef up something else, effectively making a more formidable tank, I would no longer be able to Animate the Belle from my Scrap negating in its entirety one of Seamus's abilitys. (I always have Seamus in mind for this Belle stuff) so Im going to stand firm on my thoughts on the Rotten Belles. I like them, Ill run one for character but at the current state of the game I just cant seem to find a good enough reason to not replace them with something that fulfills this same role in a more efficient way.