I think it is probably lack of water or temps. I am leaning towards temps, just because you said they were ventricosa and they are the sherman tanks of nepenthes. The brown spots look to originate from the veins which seems to tell me that the issue is from within and not an external attack. Ventricosa is technically a highland nepenthes. Although it will grow like a weed in most any condition. That tells me that humidity is probably not the issue since I grow mine if lower humidity. The next possibility is tempurature. You are in zone 9, how cold does it get there during the winter? Most neps, with the exception of a very few (2 that I know of khasiana and lamii [i think]) can withstand temps below 45. I had a ventrata burn at the growth points this fall when temps got below 50. It is doing fine now and started to branch and vine as a result, but I was nervous for a few weeks. (I haven't lost a nep yet.) Ventricosa if a very forgiving plant when it comes to water and light, but you should never let a nep dry out. Which judging by your experience, I am guessing is not the issue. That is what keeps leading me to tempurature. If that is the case, I think as long as you give them attention and get back to optimal conditions, they should bounce back. Leaves may die, but as long as new growth appears, then you should be ok. In it's weakened state try not to overwater. If leaves are dying, this is food for fungus now all it needs is a nice drink. If it is lack of water, then you should be fine too. Just make sure not to water log it for the same reasons as just mentioned. A little more light may help during the healing phase if the pitchers weren't already a reddish color before this problem. Otherwise, light is just right. Hope this helps...

The room is 12 x 12, so not too big and one window. It tends to be dark. It has wood paneling and crown throughout. The smoke damage has been determined to warrant a refinish/cleaning, not a replace. The floors will be replaced due to smoke between crevices in wood. Ceiling is also being replace. Wood is not beautiful, but overall effect is nice for a small den with one wall built in bookshelves, a set of small double doors (no glass) and a back door out the other side of the room. I am sorry I don't have a better picture, but I am not in the house currently.

Your favourite houseplant appears to be an unplanted sprouting sweet potato. I can't help with care since I eat them, not grow them. But in the right climate they are large outdoor vines. One thing you can be sure of ... in order to live a plant needs to be planted!

Cut back the dead and don’t fertilize until you see new growth. I’m one to not fertilize a stressed plant. It hasn’t been the greatest of springs in NJ, cold and rainy. We usually have much more growth and bloom by now, but it’s slow going so far. I’ll check around the local brain trust to see how this one does in the area. I don’t know many who grow it (perhaps because it is borderline hardy).