Pretty much always the case, isn't it? We see some movie at 4, 5, or 6 years old and it scares the bejeezus out of us.
You watch it years later as an adult and literally LOL at the creative if awkward uses for foam rubber, blood that looks like Heinz tomato sauce, plastic severed limbs (probably lifted from mannequins), and the worst imaginable examples of "acting", directing, and cinematography.
IOW.....they sucked.
I know what you mean... Movies that I saw that when I was little that scared the willies out of me, though I haven't seen them since... I am fairly certain that I would find them cheesy and not very scary, which is why I don't want to see them today...
"Valley of Gawangi," about some cowboys who venture into a lost valley to bring dinosaurs back for a circus or something, "Day of the Triffids" which scared the willies out of me, and made me want to live in a submarine are just two that come to mind off-hand.
Mark