That would depend if they block light or if it just travels right through them (ignore the fact that in any case anything done that would prevent a reflection would also prevent direct observation). Given the popular portrayal is mirrors do not just have a black silhouette of vampires, I think it would just travel straight through.
Something has to be there, either we see through them (same as the wall behind), or a silhouette filled with something else like pure black or madness inducing colors never seen before.
if they don’t have a reflection wouldn’t the left arm simply not be there?
That would depend if they block light or if it just travels right through them (ignore the fact that in any case anything done that would prevent a reflection would also prevent direct observation). Given the popular portrayal is mirrors do not just have a black silhouette of vampires, I think it would just travel straight through.
Something has to be there, either we see through them (same as the wall behind), or a silhouette filled with something else like pure black or madness inducing colors never seen before.