This is quite sad.
Yes, it is a non-scientific CNN poll. But CNN polls usually bend slightly left of center, so the fact that so many respondents have a negative view of unions may underestimate the actual sentiments of the general population.
What is so sad about this is the fact that it is quite likely that many of the respondents *profited* from the work of unions, via better working hours, safety measures in the work place, health benefits they did not have, higher wages for both union and non-union jobs, and so forth.
Certainly unions bear some of the responsibility for this perception problem that causes unions to be viewed negatively by such a large number of people; and the mainstream media rarely present a balanced view of the positive work that unions have done and continue to do.
But the perception is also a product of the assault that conservatives have waged against unions for the last forty years, which peaked in the Reagan years and has steadily continued ever since. The fact is that Republicans know that at least two things are true: unions are a barrier and a safeguard against a number of destructive business practices aimed at maximizing profits to the detriment of everything and everybody; and, unions are one of the best answers Democrats have to the crushing supremacy of Republican moneyed interests in election cycles, due to the organizing and mobilizing work that unions do to bring voters to polling places.
Demean and fight the ever dwindling power of unions at your peril.