From the Tweet (article): "Between 1908 and 1940, Sears managed to sell over 70,000 DIY homes' and "Remarkably, almost 70% of these Sears DIY houses are still standing today." That would mean around 49,000 are still standing.
many have extensive renovations, others are essentially standing as-built. typically they are worth millions, but that's more about geography and zoning than the construction itself.
i have lived in a few, all with the original plaster, and a mix of original plumbing/electrical. generally i would say even the mostly-original ones were are some of the nicest places i've ever lived, but that's not saying much.
there is definitely a survivorship bias, but the ones still standing seem to have weathered the moisture well. much of the ~70/80s era construction i have seen seems to have fared worse, and the new construction i've seen is downright laughable.
>typically they are worth millions
That might be just a more generality of single family homes in the Seattle area than a nod to their craftsmanship.
Bathrooms have usually been gutted though, if for nothing else than the common designs had windows in the bath/shower and pretty much guaranteed water damage in the wall.