Gallup conducts annual surveys to assess employee engagement, and distinguishes three categories of engagement. In the most recent Gallup survey (also available here), they report that “28% of
American workers are engaged, 54% are not engaged, and 18% are actively disengaged”.

The tweet above – “i hate my job i need to get a better one soon !!!!!!!!!” – reflects what I would categorize as active disengagement. As you note in your commentary, this sort of expression of disdain may be temporary, but I, for one, would be disinclined to hire such a candidate, as in my experience, anyone who has badmouthed one employer (or position) is likely to badmouth future employers (or positions). And while active disengagement can be situational, it can also be serial. I had a peak at the tweetstream for the person whose tweet you quoted above; she has also recently expressed boredom with lunch in exclamatory fashion and a state of inebriation in a NSFW fashion.