I have 100 sneak all perks and boots of muffle and i still get seen all the time in any kind of light exept by low level bandits and other low level creaures and im always seen when im bumped into

If you bump into someone they'll definitely notice you.

I'm a Vampire with maxxed and perked Sneak. Marcurio and I were sneaking around (he has high Sneak, also, and is smart enough to cease his chatting when we're sneaking), and I was feeling kinda confident with a flat detection reticule, when Marcurio coughed! I was both annoyed and delighted to see the eye immediately open.