What are spiders and other bugs doing exactly when you spot them just standing there on your wall?

Question

They just sit there, what the h**l are they in the process of doing? Are they pondering their next move? There's no prey around or anything, they just stay there, waiting for you to get bored and leave, but THEN what do they do?!

Answer 1

Maybe they're digesting something.  Maybe they're thinking "this place isn't as nice as under the table ... should I go forward? go back?".  Maybe they're wondering what that great big giant monster is doing standing still and watching them.    Maybe they're resting/sleeping.

Answer 2

Often times they don't even comprehend you.  They don't have the best of vision unless it is a wolf or jumping spider, and you are too big for them to be able to differentiate you and the background.  

They are most likely just chilling until something comes along and makes it flee or offers it food.

Answer 3

they do this

http://www.youtube.com/watch?v=sHzdsFiBb...

Answer 4

They wait until you go to sleep and then raid the liquor cabinet and fridge