One thing I'm learning: Spiders really know how to hide. Their costumes are much more subtle than the average Halloween attire.
These are the only spiders that regularly flaunt themselves in plain sight. Most are a lot more subtle.
Take Dark Legs (a female zygiella x-notata). Can you see her up there? She has her legs resting on her "doorbell," a line of thread leading to the center of her web, but she herself gets to stay out of site.
How is that? Just a bunch of twigs, right? No spider at all.
That better? All that's really visible is the legs, just so long as you know where to look.
And here is Little Brown, an Araneus montereyensis, during the day, perched by the side of a twig, pretending to be a bit of bark or a drift of debris.
See? There she is!
Even larger spiders, like the Neoscona, can be hard to find. Just a lump in the brick: