Is THIS how you imagined the vampires?

[Sir Kohran]

Morthoron, there's enough examples on here now to show that Tolkien equating light with good, dark with evil was anything but consistently shown!

Maybe. But there are many more examples that show that Tolkien generally equated white/light with good, black/shadows with bad. It's an idea that he constantly used, and not just in LOTR - for instance, when good Fingon dies, his white helmet is broken in a white flame by evil Gothmog's black axe. Whilst there may be exceptions to the rule, the rule was there and was generally prevalent - white things are mostly good, black things are mostly bad. Heck, just looking at the cover of LOTR in front of me, the Ringwraiths have jet black cloaks. It's a common motif throughout the story.

the bright flames at the heart of Mount Doom

I must disagree.

At first he could see nothing. In his great need he drew out once more the phial of Galadriel, but it was pale and cold in his trembling hand and threw no light into the stifling dark. He was come to the heart of the realm of Sauron and the forges of his ancient might, greatest in Middle-earth; all other powers were here subdued.

Whilst the flames might be bright, the cavern they inhabit is dark and black.