Wilted Spinach doesn't mean it's gone bad so eating wilted spinach will not make you sick.
The Wilted Spinach is okay to cook and eat as long as it has not actually gone bad but if the spinach is just wilted then it's okay to eat.
When spinach has actually gone bad enough to make you sick from eating it you'll certainly know when it's gone bad.
Spinach goes bad when the edges of the once bright, crisp green leaves first turn yellow, and eventually, the leaves will get gnarly and soggy, often taking on an unpleasant smell.
When that happens the spinach is bad and should be thrown out and not eaten.