This never reflects well on you, or your argument. It also plants the idea in the mind of your audience that perhaps people who believe like you all suffer from a weak and/or corrupt mind. This is not a fair observation, but it is a likely one. If you want to advance truth, you care more about effective persuasion than hurting your interlocutor.
It is rare I find myself in a discussion of any seriousness without someone resorting to personal attacks, ridicule and simple name-calling. I do not think the guilty parties recognize how bad this is for themselves, and their ideas.
First, when you engage in one of these activities, you are showing the entire audience-not just the person you are attacking, but everyone who will ever read those words-that you are either ignorant on the matter at hand, and unable to articulate an argument, or of such poor character that you cannot resist the temptation to attack the person, rather than their idea. You get pleasure from insulting them, but care not for advancement of truth.
Secondly, the personal attack represents a violent approach that, on the surface, suggests you are incapable of argumentation, and thus, must resort to violence to get your way. In other words, you are a bully. If you don’t know the difference between a bully, and someone who is simply strong, then you might be guilty of this. A bully rules through fear and force. A strong man rules through power. There is a difference between power and force.
Third, if you resort to these behaviors, you are showing yourself to lack self-discipline. If you are not in control of the words you write or speak, you are not in control of your mind, and thus you are proving yourself unworthy of participation in the conversation. It is simply verbal diarrhea. Who needs that?
These are principles every child should know by the age of reason. They may not be easy to conform to, but they should be accepted as reasonable guidelines for behavior. Teach your children and those you influence, and if the requirements for civilized, mature conversation are out of your reach, just abstain from conversations that prove too much for you. None of us are above falling into these errors, but we can at least hold these virtues above ourselves and strive to acquire them.