
Barbara K. answered 02/15/20
Writer, Reader, Speaker
Spot is the only one of your three words that is most often a noun, though all three can be either a noun or a verb.
See is more commonly a verb, as in the three-word sentence from an American English reading textbook as old as I am, It can be a proper noun to refer to a religious jurisdiction, especially the Pope’s “Holy See.”
Spot can be a verb that’s very similar to the verb to see, as in “I spot a problem with your idea.”
Run is usually a verb, as in “I run to work.” It can, however, be a noun referring to the act of running (“I get my morning run on the way to work”) or the place where running happens, especially for animals, such as a dog run.
The “who, what, ...” guide you cited is more useful for the parts of a narrative. “Person, place, or thing,” as Jennie noted, is a better rule for identifying a word being used as a noun.