+1
I generally find that I can enjoy horror films whether they age well or not. There's an obvious quality of corniness in those that don't age well, but there's also a certain kind of aesthetic pleasure in them too.
For instance, I don't think that Frankenstein, Night of the Living Dead, or The Evil Dead have aged all that well, but these are still classics in every sense.
Ones that have aged exceedingly well though and still scare, for me at least:
The Exorcist
The Texas Chainsaw Massacre
Vampyr
And although it might not be old enough to warrant it's inclusion, something like The Shining still works exceedingly well, of course.