That cartoon is kind of funny, is it not? Though for a pastor's wife it is also kind of true. There have been a couple of people over the past 22+ years in ministry that I've wanted to throttle. But God took care of them, more on that later.
This is what unkind words said about your pastor can do:
First of all, they reflect back onto you. Everyone knows that someone given to gossip will talk about anyone. All you have to do is give them ammunition and watch them go.
Unkind words about your pastor can damage your church, not only within its walls, but in your community. Yes, your pastor is human and will do human things (just like you do...) but he is trying to live his life in a way that is pleasing to God (just like you should be doing...) What does it tell your community when they hear you talking bad about your pastor? They already think that Christians are hateful, don't give them more lies to believe.
Your words can interfere with his vision for the church. When he hears the murmurings and division he isn't as focused on what he should be. Instead he has to try to fix things. His energy is better spent on shepherding instead of mending fences.
Your words can cause him physical illness. They can put a strain on his marriage. They can cause his children to walk away from their faith.
You may disagree with him but be careful what you say.
There have been times when I've seen this played out.
The person who was going around town talking about my husband (her pastor),
"There's a devil in that pulpit and we won't go back to that church until the devil is gone."
Within a week she was in the hospital with a ruptured colon.
Another had several heart attacks and soon after, died. Another had cancer.
Be careful with your words when you're talking about those who God has anointed.
In fact, your best bet is to just pray for them. If it's something that you feel needs to be discussed then arrange to meet with them face to face.
Don't spread stories. Don't pass judgement. It will not do what you want it to do.