Yeah, they're like any other movie, old or new, in that some just don't pique my interest. But for me a good part of it does seem to be whether I'm in the mood for a silent film.

For example, I recall starting to watch an old Chaplin film - I believe it was The Kid - and just finding it boring as heck. Months later, I was channel surfing and came across it and was able to enjoy watching it.