How easy is it to conduct unscientific polls and insert bias into a poll at every question?

How easy is it to conduct unscientific polls and insert bias into a poll at every question? What issues might these unscientific and biased polling methods present? How do they impact the reporting of public opinion?

Book for course is The Enduring Democracy
Kenneth J. Dautrich, David A. Yalof, Christina E. Bejarano, 2020
Sage