Correct. This one is a no brainer.
Put more scientifically, it means that it is impossible to use one's day to day experience as a truly random sample. There are going to be variables (like comfort level in showing the goodies given media driven expectations of what such goodies should like) which will skew the randomness of the day to day experience.
I mean, would you use what you saw in porno films as a good basis for what the everyman is packing? No.
Yup, I totally agree.
Guys with bigger cocks will be more open about it than a guy with a small penis. I figure that would be a given.