The standard rule is that no cooked food should be left out for more than two hours before it is refrigerated. For safety's sale, that rule should be followed.
Yes. It takes a long time for bacteria to form on this product. It will spoil if left out of the refrigerator. It will dry out if left uncovered.
It can grow mold if it is left unrefrigerated for a long time. But it is unlikely to spoil otherwise.
It really should be refrigerated at all times because it could spoil,it should not be left out for more than 2 hours.
Toasted bread does not spoil! it molds!
Only if it is left out a long time to ferment or spoil.
2 days
It does if you keep it long enough!
The question properly would be "How do apples spoil?" Eventually, they will turn brown or get brown spots on them if you leave them in the refrigerator too long... Try to use them before they begin getting brown spots. And frankly, you can still eat them and bake with them -- just cut away the brown spots. But I wouldn't ...
Salmon will not last very long when it is left unrefrigerated. It will spoil within the same day. Salmon will last up to two days in the refrigerator, or if cooked, will last up to four days.
3 months
Four hours at room temperature after that it begins to spoil.
2-4 hours is about how long it will take for liquid coffee creamer to start to turn (spoil). At the grocers I work in, anything perishable (especially dairy) that is left out and unrefrigerated for an hour is deemed unfit for sale and thrown out.