I suspect that UCSC suffers because a lot of parents formed their impressions of the school back in the 1970s and 1980s, when they were looking at colleges themselves. At that time, a California kid could slack off in high school and still get into UCSC. The acceptance rate was over 80% as recently as 2002.
For comparison, UCSC is currently reporting 24,469 admitted freshmen out of 52,516 applications for Fall 2017 which represents an acceptance rate of 46.6%. Those aren’t the final numbers; they could go up slightly if UCSC takes students off the waitlist.
https://admissions.ucsc.edu/apply/first-year-not-admitted.html
But the point is that admission to UCSC is now far more competitive than it was historically. It’s reasonable to assume that this shift has worked to the disadvantage of the stoners and slackers, and so the common parental view of UCSC is outdated.