People or things that were perceived as negatives were often referred to as "bummers." For instance, if someone went somewhere such as a party and the person did not enjoy himself, he would describe that party as a "bummer."
The hippie era left us with lots of new jargon and language, some with negative connotation and some not. Some of these words came from the music of the era, others just appeared as if from nowhere.
Another word that was used to express negative feelings was "drag." If a person was a "drag" it meant that they were not pleasant to be around and were not "cool." You could also call a person like that a "dip" or a "dip stick."
If we are looking for Hippie style language that was used to express negativity, we might go to what the movement disliked. The notion of "being a square" reflected the desire to break through the conformity that was perceived as such a large part of society. Being "straight" was perceived as a negative because doing so took away from the basic elements of freedom and expression. When Frank Zappa encouraged hippies to dress in a more "earthy" and unique manner, he admonished his audience for "wearing a uniform," meant to indicate that what conventional social expectations are for fashion help to conform and reduce individuality. Individuals who embraced the social order and the perceived conformity with it were "out of touch." To these ends, members of the military were called "baby killers," to bring about the negative perception of the military and the war in Vietnam. For those who brought about negative energy, they possessed "bad vibes." Finally, the "narc" was the derogatory term applied to anyone who might be seen as an informant of the police or to a square in the presence of other hippies.
Cool, far-out, groovy, awesome, out-a-sight!!!