Stealing a marketed item may not make you a horrible person but it is a horrible act. In this day and age you are lucky that there is a brick and mortar magic shop within your area that you can just go and drop by, they are getting few and far between. You should probably be supporting them rather then stealing from them, (I'm assuming that he was showing you an effect he was trying to sell and not just showing off behind the counter).
The other night I was watching a comedian and he was doing a fantastic routine. I figured out all the words and the timing and now I'm using it. Is that stealing? (no, I did not really do that).
In the end you can only be your own moral compass. How others judge you is soley based on your actions. As previously implied, the fact that you made the post tells me that somewhere along the line you know the answer to the question, and you are probably looking for positive re-enforcement to clear your guilty mind. Or you really had nothing else to discuss and wanted to start some sort of debate that has been debated over and over again. I'll probably get blasted for this post because it is nothing that anyone who steals wants to hear, blast away justify your theft but don't look for my rebuttle. As this post stands on its own. Agree, disagree, its up to you.
And yeah, I'll probably be joining you in hell. But odds are it won't be for stealing.
