I was basically right that it's both poor literary analysis and poor history. A lot of statements about what Stoker knew about the historical Dracula are pure assertion or speculation. Phrases such as 'It is likely Stoker heard the legends connecting Dracula to this region' (Bistrița) abound. And much of the information about the historical Dracula is completely unreferenced, which is hopeless when the primary sources for him are so contentious. They need not just referencing but constant direct engagement and discussion to get anywhere. McNally and Florescu are sometimes capable of doing that, but not consistently enough, and in particular they seem to have a complete blind spot when it comes to Romanian oral folklore. They treat this a reliable source which can be used to 'confirm' stories from the manuscripts and printed pamphlets, without considering that the folklore legends may stem from people reading the same sources centuries ago. Regarding the location of Dracula's supposed grave at Snagov, they even literally say 'We are inclined to accept the idea that the actual grave was the one near the altar, the one sanctioned by local folklore - always a useful guide in resolving enigmas associated with Dracula' (pp. 113-4). No. You cannot do that. Oral history is just not a reliable source over those timescales.
I was right that this was where Peter Tremayne got the idea about a second castle in the Argeș valley, but this is one of the claims which McNally and Florescu only really have oral tradition to support. According to them, local tradition in the area of Poenari castle claims that the name 'Poenari' originally referred to an older castle on the opposite side of the river from the one visible today (pp. 66-67). They say that the older castle stood on the site of a Roman-era fortress, and that its stones and bricks were used by Dracula to rebuild the castle on the other side of the Argeș now called Poenari. But they can't show any evidence of the older castle's existence - all they say to support it is that they were told about the remains of a low-lying wall at the bottom of the hill which might have formed part of its defences, and shown re-used stones in the local church and chimney-stacks and Dacian-period artefacts in the museum. There are no pictures even of any of these reused stones and artefacts, so it's basically pure hearsay, and they don't even claim to have seen the supposed low-lying wall themselves - only been told about it.
They are similarly vague and even self-contradictory about supposed underground passageways leading from the castle which is now called Poenari and out into the Argeș valley. The reality is that no such passageways are now identifiable, but they are convinced they must have existed nonetheless, because local oral tradition speaks of Dracula escaping from the castle that way in the context of a Turkish attack. So the tunnel is described on that basis (p. 72), and they also say that a visitor in 1912 reported seeing remains of the sunken passageway before the castle was damaged by an earthquake (p. 75), but don't say anything about who this visitor was or quote their account. As for who built it, they describe a winding staircase at Bran leading from a hidden stone covering next to the well in the main courtyard and out onto the knoll on which it stands, and assert that Dracula was so impressed by this that he installed something similar at 'his castle on the Argeș' (pp. 63-64). But, just a few pages later (p. 68), they claim that at the end of the fourteenth century, a Wallachian prince and his supporters retreated from the Tartars to the same castle, and when the Tartars stormed it they found nobody there, because the prince and his retinue had fled through secret passageways to the banks of the river. That story can only be true if there were already secret underground passageways at the castle half a century before Dracula's time, meaning that he had no need to install them himself.
Most of the book is like that. Much of the information in it seems interesting, but it crumbles on closer examination, just leaving you feeling irritated that you bothered in the first place. That said, I did notice for the first time thanks to this book that the St Gall manuscript about Dracula, a translation of which it contains, compares him directly to Herod, Nero, Diocletian and other persecutors of Christians. That's interesting, because I've been working on a theory for a while that quite a lot of the contents of the 'horror stories' which circulated about him is actually drawn from existing traditions about other tyrannical monarchs, and that sort of direct comparison confirms that at least some of the writers knew what tradition they were writing in. I also learnt from this book that one of the best-known portraits of Dracula comes from a collection at Ambras Castle in Austria specifically put together as a collection of curiosities by Ferdinand II, Archduke of Tyrol, which also includes the well-known portrait of the so-called wolf-man, Petrus Gonsalvus and his children. I knew it was called the 'Ambras portrait', but wasn't aware of that wider context, which is of course very typical of how almost every aspect of Dracula and his story has been perpetuated over the centuries. The castle, and Innsbruck where it is located, both look lovely, so I must try and go there some time once that sort of thing is possible again.