Miguelito,
These theme parks are not only about roller coasters and that kind of thing, they're not your regular 'parque de atracciones', they're a more "complete" form of entertainment. I confess I enjoy them very much (feeling like a kid again) and BELIEVE ME I won't ever be cought in one of those torture devices!
Tip: you can always bring 'bocadillos' with you, and I doubt that anybody'd ask you whether they're homemade or you bought them there!