How does an irrational argument affect your opinion about the original premise?

Having seen my share of heated debates here turn bitter and irresolvable, I wondered if we might look at the whole process of debate, logical thinking, argument and fallacious logic outside of the emotion of any particular issue and perhaps avoid a few such impasses in the future. That is the purpose of this question. So, in that spirit, here are the question details.

In your eyes, does backing up one fallacious argument with a chain of additional logical fallacies strengthen or weaken the case for validity of the original premise? For instance, let’s consider the statement A = B and B = C. Therefore, A = C. If it is true that A = B and that B = C, then by the principle of equivalence, A = C must be valid. However, it is possible that A does not = B and B does not equal C and yet A = C is still valid. It is simply unproven in that case. The Skeptic’s Guide to the Universe provides a good introduction into rationality and logic, and an interesting list of the 20 most common logical fallacies.

If you routinely find yourself resorting to, and being called for using logical fallacies to support an assertion you have made in a debate here, you might consider studying the Skeptic’s Guide list of fallacies and how logical reasoning properly works. It is no fun to debate when you get nailed for lousy logic over and over again. And it puts you at risk of holding beliefs and opinions that you reached not by rational thought but rather by reverse engineering—starting with a conclusion you wanted to be true, then trying to build a structure of premises and logical arguments to support it. While it is possible to get lucky and be right using that method, the chances are that most often it will lead to supporting conclusions without any underlying facts that lead to the conclusion, conclusions that are most likely invalid.

So how do you react when you find a fellow Jelly supporting some pet position with an unending string of ad hominems, arguments by assertion, tautologies, and circular reasoning? Do you feel it is worthwhile to learn solid logical principles, or are you so certain you will always start with a conclusion that is true that you feel no need to examine positions, just state them then fight to justify them any way you can?