A professor once told our class that words don't have meaning... they have usage. If someone asked you for a 'Plug," what are they requesting? There are about nine different usages in the English language (including slang) for the word "plug."
A plug can be an electrical chord or outlet. A plug can be an encouraging remark on their behalf. A plug can be a pinch of tobacco. A plug can be an old horse, etc.
I've discovered that most people in business use words without thought to the usage and claim a common meaning. For this discussion we need to understand the difference between ignorance and stupidity. Ignorance and being ignorant, refers to someone not having prior knowledge or education on a subject. Stupidity is knowing but acting contrary to the knowledge.
1. When they say, "That's a good question!" it actually means that they don't have a clue what the answer is, or have never thought about it before. They say this to stall you because they don't know what to say. It is actually a way of displaying ignorance. They have no idea what you are asking and are showing in a positive way that they don't know what to say otherwise.
2. When they say, "I've always heard that expression!" it actually means ignorance runs in their family or upbringing. They are pleading a lack of knowledge of the facts. I spoke with a man one time who used the word, "frustrated." He used it when he didn't understand how to solve a problem. Apparently he thought it was a combination of flustered and frustrated. There is no such word. He was in business and would use this phrase often. When someone would point out the word, he would indignantly use it more often, then say, "I've always heard that expression all of my life!" I wouldn't brag about that to outsiders.
3. When they say, "I don't make decisions, I just pass the information along to the committee." they actually mean that they have responsibility with no authority in their job. The committee is there to use authority and this person is in a support position, but wants more authority. They won't get it as long as a committee is in control, though. People who say this also are usually frustrated with a powerless job in which they can't make decisions without asking "Mommy and Daddy" (the committee) permission. They feel subordinate to a group of people they resent for having the authority to make decisions that reflect on the person who said this.