Opinion polls involve a choice. The people who are being asked to take the poll can say yes or no.
I suspect that this leads to such a significant amount of self-selection bias that I am starting to think that most opinion polls are by and large misleading due to them representing the views of the extreme and not the average. Am I correct in this position?
Here's what I mean. If you, say, call up a person and ask for five minutes of their time to do a poll, most likely they'll say no thank you. Most people ... just aren't interested in doing polls, right?
So if a person actually says yes, that would suggest that this person is abnormal in the sense that they actually want to do the poll. Why would that be? Well, there are many possible reasons (lonely elderly, perhaps?), but certainly one possible reason is that this person just happens to have an extreme opinion on the topic that they are about to be polled on, and therefore has an increased interested in making that opinion known. The average person, having the average opinion, will therefore be underrepresented in such polls, while the extreme person will be eager to express their extreme opinion
For example, if I received a call today from a pollster asking for a few questions on "LGBT", I'd pass. I have no strong opinions on the topic, am not LGBT myself, nor do I hate LGBT members. It's just not relevant to my life, so I have little to say. However, if I happened to be LGBT myself, or if I happened to be somebody who strongly disliked the LGBT community, I might very well be interested in taking such a poll. Hence the poll becomes skewed and representative of more extreme opinions.