EDIT - new pic attached to bottom
I've got a billion nodes making a texture that covers most of the robot. i want to animate it tho, and the poota chuggs even when moving things around in viewport, so i believe baking the texture on to each mesh will free up processing power. (i have another post up regarding animation misery)
baked image size is 2048, tile size 2048, 64 samples. Object has been unwrapped and looks good when all the nodes are plugged in. the resulting diffuse is f*&#ing awful tho.
I cant see what i did wrong
on another note, all the youtube vids suggest exporting diffuse/bump/aoc etc seperately. why not just use combined? - see answer below
UGH.. so, i found i was unwrapping the wrong hip (local camera in uv unwrap pointed at the wrong hip). the poorly setup AOC was prolly making it darker than expected, and i had overlooked the metallic in the rust part, mixing with the rest of the bake.