"I never tell them what I really think"

my acquaintance told me.
We were standing in the shopping centre. She had just been bailed up by someone with a clipboard - someone who was doing a survey. Apparently it was some sort of "environmental" survey this time. Of course I had not been stopped. I am never stopped. 
It is a curious thing. Charity collectors never seem to mind asking me for money but people doing surveys never want my opinion. 
I wonder if I would give them an honest answer if they did ask me?
During the election campaign we were phoned more than once, mostly with automated messages from politicians. I just put the phone down on these - something I suspect most people did. But there was one phone call from the national broadcaster wanting me to answer some questions for Q & A. Before the young man  at the other end had a chance to ask me any I had to regretfully tell him I couldn't answer them. I was regretful because I would like to have known precisely how he would have phrased the questions.  I already knew what sort of answers he would be looking for. I know what sort of material they can use in a program like that. They don't want the sort of answers I would give and they couldn't use them. Unlike the person who had stopped me to ask something else I am not prepared to give them the answers they want - to lie. 
But people do lie, especially when they are face to face with the interviewer. They may simply believe they should answer in a certain way or they may not want to share their opinions or they feel they will be criticised for holding a different opinion from the socially or politically acceptable one.
And of course the questions can be designed to elicit answers that the surveyors want. I once had a long conversation with someone who was responsible for the Morgan-Gallup polls in Downunder. He admitted that questions could be crafted in this way - and used in an effort to change public opinion. I asked him how many people he thought lied when they answered. He had no idea but said he thought most people told the truth and that had to be good enough.
I was left wondering just how valuable surveys and opinion polls are. Presumably they are sufficiently valuable to keep on doing them.
I remember asking once at a disability advocacy meeting how many people in the room had been stopped and asked for their opinion by a person with a clipboard in the street. There would have been well over a hundred people at the meeting - a day long conference. The only people who put their hands up were people who were not disabled or did not have a visible disability. We agreed that, in general, people with disabilities won't be asked. Perhaps people with disabilities are not supposed to have opinions?
I wondered whether I should chase up the young man with the clipboard and demand to give him my opinion. If he had stopped me would I have told him what I really think? I don't know because I don't know what the questions were. I would probably just have said "I can't answer that" if it was a question I didn't want to answer.
But out there in the street they will probably never get my opinion about anything because I will almost certainly never be asked.  I make up for it here instead.