What if people understand or interpret words differently in their mind? Let's think about it, we have all adopted to learn the meaning of words through experiences or emotions. We didn't learn each and every word from a dictionary. What if I understand a word slightly differently in my complex mind? Could it result in some sort of pessimistic or optimistic or abstract outcome? And how often is this case true in our society?
Quite certainly this is the case (even if you learn all words from a dictionary), but this is more of a philosophical debate. It is unclear what you are after when referring to 'pessimistic', 'optimistic', or 'abstract' outcomes, but I can point you in the right direction in case you want to read up more on this subject.

One concept that comes to mind from linguistics and philosophy of language is  indexicality.


  ... an indexical behavior or utterance points to (or indicates) some state
  of affairs. For example, I refers to whoever is speaking; now refers to the time at which that word is uttered; and here refers to the place of utterance.


However, some argue the same holds true for almost any utterance. (Suchman, 1986)


  Among philosophers and linguists, the term indexicality typically is
  used to distinguish those classes of expressions whose meaning is
  conditional on the situation of their use in this way from those such
  as, for example, definite noun phrases whose meaning is claimed to be
  specifiable in objective, or context-independent terms. But the
  communicative significance of a linguistic expression is always dependent on the circumstances of its use. A formal statement not of
  what the language means in relation to any context, but of what the
  language-user means in relation to some particular context, requires a
  description of the context or situation of the utterance itself. And
  every utterance's situation comprises an indefinite range of possibly
  relevant features. Our practical solution to this theoretical problem
  is not to enumerate some subset of the relevant circumstances—we
  generally never mention our circumstances as such at all—but to "wave
  our hand" at the situation, as if we always included in our utterance
  an implicit ceteris paribus clause and closed with an implicit et
  cetera clause.



Suchman, L. (1986). Plans and situated actions. New York, Cambridge University.