The word starts with a capital letter indicating it is a name (most likely a pet). A proper noun is the name of a person, place, or thing. If Spot is the name of something, then it is a proper noun.

A noun starting with a capital letter is not always a guarantee that it is a proper noun, people do get it wrong, so you must know the context of the noun's use. For example:

The new puppy, Spot left a spot on the carpet.

The blind spot as you call it. Is generally cured by proper set up of your mirrors and also adding small covex mirrors externally.

The proper term of a sweet spot is defined as a particular area on a baseball bat, racket, or club that makes the best shot available. It is usually used when playing sports.

A 'spot check" is a random sampling to gather infiormation to determine an outcome or on which to base an action.

(For instance: Police may conduct random 'spot checks' of motorists to determine their compliance with having proper insurance, vehicle registrations, or drivers licenses in their possession.)