Being an idealist and harsh cynic seems to be a huge contradiction but if you understand that the cynicism is a means to identify pitfalls to the idea, it makes a little more sense. Find the flaws and bring the goal into existence.
ISFJs are sincere and considerate individuals, with extremely warm hearts. No one gives quite like the ISFJ. ISFJs are capable of melting even the coldest of hearts, simply with the love and warmth that they possess within themselves.
And if you point it out to someone (who doesn't see it yet) they look at you like you have two heads. Eventually, the "secret" fakeness comes out, though. And you're just sitting there like, "I TRIED to tell you something was off with that person!