Polls have two major flaws -
1. They are only as accurate as the poll participants are honest (e.g. 2016 Presidential Candidate Poll).
2. The person who writes the polls designs them in such a way to bolster and argument.
Here is a classic example of #2 int he form of the age old "gun control" debate -
"Do you A) Think we need stricter gun control laws or B) Think our current laws suffice?" Notice that there isn't a "C) Think our current gun control laws are too restrictive."
That's why I cringe when I hear people citing polls as evidence to prove an argument.